Статті в журналах: "0D-1D simulation"

1

Simakov, Sergey S. "Spatially averaged haemodynamic models for different parts of cardiovascular system." Russian Journal of Numerical Analysis and Mathematical Modelling 35, no. 5 (October 27, 2020): 285–94. http://dx.doi.org/10.1515/rnam-2020-0024.

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AbstractThis paper revisits the usage of spatially averaged haemodynamic models such as non-stationary 1D/0D in space and stationary 0D in space models. Conditions of equivalence between different 1D model formulations are considered. The impact of circular and elliptic shapes of the tube cross-section on the friction term and the tube law is analyzed. Finally, the relationship between 0D lumped and 1D models is revealed.

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2

Alastruey, Jordi, Nan Xiao, Henry Fok, Tobias Schaeffter, and C. Alberto Figueroa. "On the impact of modelling assumptions in multi-scale, subject-specific models of aortic haemodynamics." Journal of The Royal Society Interface 13, no. 119 (June 2016): 20160073. http://dx.doi.org/10.1098/rsif.2016.0073.

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Simulation of haemodynamics has become increasingly popular within the research community. Irrespective of the modelling approach (zero-dimensional (0D), one-dimensional (1D) or three-dimensional (3D)), in vivo measurements are required to personalize the arterial geometry, material properties and boundary conditions of the computational model. Limitations in in vivo data acquisition often result in insufficient information to determine all model parameters and, hence, arbitrary modelling assumptions. Our goal was to minimize and understand the impact of modelling assumptions on the simulated blood pressure, flow and luminal area waveforms by studying a small region of the systemic vasculature—the upper aorta—and acquiring a rich array of non-invasive magnetic resonance imaging and tonometry data from a young healthy volunteer. We first investigated the effect of different modelling assumptions for boundary conditions and material parameters in a 1D/0D simulation framework. Strategies were implemented to mitigate the impact of inconsistencies in the in vivo data. Average relative errors smaller than 7% were achieved between simulated and in vivo waveforms. Similar results were obtained in a 3D/0D simulation framework using the same inflow and outflow boundary conditions and consistent geometrical and mechanical properties. We demonstrated that accurate subject-specific 1D/0D and 3D/0D models of aortic haemodynamics can be obtained using non-invasive clinical data while minimizing the number of arbitrary modelling decisions.

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3

Naidis, G. V., and N. Yu Babaeva. "Low-pressure CO₂ discharges: 1D modeling." Physics of Plasmas 30, no. 1 (January 2023): 013506. http://dx.doi.org/10.1063/5.0130672.

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A 1D model of glow low-pressure CO2 discharges is developed. In the framework of this model, simulation of stationary and repetitively pulsed discharges at pressure ranging from 0.5 to 5 Torr and current from 10 to 50 mA is performed. The obtained plasma characteristics are compared with the available experimental results and with the data evaluated based on the approximate 0D approach. The results of 0D and 1D calculations agree for most of plasma parameters, except for the molar fraction of CO molecules produced at CO2 dissociation by electron impact. Agreement between the measured and calculated, in the framework of the 1D model, values of the CO molar fraction is provided by modifying the expression of the dissociation rate constant vs the reduced electric field.

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4

Echeverribar, Isabel, Pablo Vallés, Juan Mairal, and Pilar García-Navarro. "Efficient Reservoir Modelling for Flood Regulation in the Ebro River (Spain)." Water 13, no. 22 (November 9, 2021): 3160. http://dx.doi.org/10.3390/w13223160.

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The vast majority of reservoirs, although built for irrigation and water supply purposes, are also used as regulation tools during floods in river basins. Thus, the selection of the most suitable model when facing the simulation of a flood wave in a combination of river reach and reservoir is not direct and frequently some analysis of the proper system of equations and the number of solved flow velocity components is needed. In this work, a stretch of the Ebro River (Spain), which is the biggest river in Spain, is simulated solving the Shallow Water Equations (SWE). The simulation model covers the area of river between the city of Zaragoza and the Mequinenza dam. The domain encompasses 721.92 km2 with 221 km of river bed, of which the last 75 km belong to the Mequinenza reservoir. The results obtained from a one-dimensional (1D) model are validated comparing with those provided by a two-dimensional (2D) model based on the same numerical scheme and with measurements. The 1D modelling loses the detail of the floodplain, but nevertheless the computational consumption is much lower compared to the 2D model with a permissible loss of accuracy. Additionally, the particular nature of this reservoir might turn the 1D model into a more suitable option. An alternative technique is applied in order to model the reservoir globally by means of a volume balance (0D) model, coupled to the 1D model of the river (1D-0D model). The results obtained are similar to those provided by the full 1D model with an improvement on computational time. Finally, an automatic regulation is implemented by means of a Proportional-Integral-Derivative (PID) algorithm and tested in both the full 1D model and the 1D-0D model. The results show that the coupled model behaves correctly even when controlled by the automatic algorithm.

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5

YUHN, Changyoung, and Marie OSHIMA. "Effects of reducing 1D network complexity in a 1D–0D simulation of cerebral circulation." Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME 2019.32 (2019): 1A22. http://dx.doi.org/10.1299/jsmebio.2019.32.1a22.

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6

Dilber, Viktor, Momir Sjerić, Rudolf Tomić, Josip Krajnović, Sara Ugrinić, and Darko Kozarac. "Optimization of Pre-Chamber Geometry and Operating Parameters in a Turbulent Jet Ignition Engine." Energies 15, no. 13 (June 28, 2022): 4758. http://dx.doi.org/10.3390/en15134758.

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A turbulent jet ignition engine enables operation with lean mixtures, decreasing nitrogen oxide (NOX) emissions up to 92%, while the engine efficiency can be increased compared to conventional spark-ignition engines. The geometry of the pre-chamber and engine operating parameters play the most important role in the performance of turbulent jet ignition engines and, therefore, must be optimized. The initial experimental and 3D CFD results of a single-cylinder engine fueled by gasoline were used for the calibration of a 0D/1D simulation model. The 0D/1D simulation model was upgraded to capture the effects of multiple flame propagations, and the evolution of the turbulence level was described by the new K-k-ε turbulence model, which considers the strong turbulent jets occurring in the main chamber. The optimization of the pre-chamber volume, the orifice diameter, the injected fuel mass in the pre-chamber and the spark timing was made over 9 different operating points covering the variation in engine speed and load with the objective of minimizing the fuel consumption while avoiding knock. Two optimization methods using 0D/1D simulations were presented: an individual optimization method for each operating point and a simultaneous optimization method over 9 operating points. It was found that the optimal pre-chamber volume at each operating point was around 5% of the clearance volume, while the favorable orifice diameters depended on engine load, with optimal values around 2.5 mm and 1.2 mm at stoichiometric mixtures and lean mixtures, respectively. Simultaneous optimization of the pre-chamber geometry for all considered operating points resulted in a pre-chamber volume equal to 5.14% of the clearance volume and an orifice diameter of 1.1 mm.

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7

Tretyakova, Rufina M., Gennady I. Lobov, and Gennady A. Bocharov. "Modelling lymph flow in the lymphatic system: from 0D to 1D spatial resolution." Mathematical Modelling of Natural Phenomena 13, no. 5 (2018): 45. http://dx.doi.org/10.1051/mmnp/2018044.

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In this study, we formulated a core mathematical model for describing the one-dimensional lymph flow in lymphatic vessels and branching network of lymphatic vessels. The 1D model was numerically implemented using the 1D haemodynamic modeling tools developed in T.M. Gamilov et al. and S. Simakov et al. [T.M. Gamilov et al., Transl. Med. 6 (2013) 5–13 and S. Simakov et al., Russian J. Numer. Anal. Math. Model. 28 (2013) 485–504]. The formulated model was calibrated using published data on lymph flow dynamics and other modelling studies of lymph flows. The comparison of 0D and 1D formulations of the lymph flow models is presented.

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8

Kovács, László, and Szilárd Szabó. "Test validated 0D/1D engine model of a swinging valve internal combustion engine." Multidiszciplináris tudományok 11, no. 4 (2021): 266–77. http://dx.doi.org/10.35925/j.multi.2021.4.31.

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In the quest for reaching ever higher power density of IC engines a much simpler solution has been investigated that allows vehicles to reach a comparable power level with cars equipped with turbo charged engines. The new Swinging Valve (SwV) arrangement enables the unhindered gas exchange process through an engine. In this experiment a flow bench was used to examine a normal poppet valve cylinder head and a cylinder head constructed for the same engine but with Swinging Valves. The flow parameters of the original cylinder head were obtained then the SwV head was investigated in the same way. To examine the practical use of a SwV system a 0D/1D engine simulation had been created, first using the engine with conventional cylinder head. That model had been validated with dynamometer tests. After this stage the results of the Swinging Valve flow measurements were fed in the same 0D/1D engine simulation then the results were compared and examined.

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9

Lebedev, Yuri A. "Microwave Discharges in Liquid Hydrocarbons: Physical and Chemical Characterization." Polymers 13, no. 11 (May 21, 2021): 1678. http://dx.doi.org/10.3390/polym13111678.

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Microwave discharges in dielectric liquids are a relatively new area of plasma physics and plasma application. This review cumulates results on microwave discharges in wide classes of liquid hydrocarbons (alkanes, cyclic and aromatic hydrocarbons). Methods of microwave plasma generation, composition of gas products and characteristics of solid carbonaceous products are described. Physical and chemical characteristics of discharge are analyzed on the basis of plasma diagnostics and 0D, 1D and 2D simulation.

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10

Najafi, M., and Z. Benjelloun-Dabaghi. "A New Modelica Model and Scicos Simulation for 0D/1D Nonlinear Complex Systems." Oil & Gas Science and Technology - Revue de l'IFP 63, no. 6 (November 2008): 723–36. http://dx.doi.org/10.2516/ogst:2008042.

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11

Zhang, Hao, Naoya Fujiwara, Masaharu Kobayashi, Shigeki Yamada, Fuyou Liang, Shu Takagi, and Marie Oshima. "Development of patient-specific 1D-0D simulation based on MRI and SPECT data." Journal of Biorheology 32, no. 1 (2018): 2–8. http://dx.doi.org/10.17106/jbr.32.2.

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12

Matsuura, Sohei, Toshio Takayama, Changyoung Yuhn, Marie Oshima, Takuro Shirasu, Takafumi Akai, Toshihiko Isaji, and Katsuyuki Hoshina. "Indication of Selective Shunting During Carotid Endarterectomy: 1D–0D Hemodynamic Simulation of Cerebral Perfusion." Journal of Vascular Surgery 72, no. 1 (July 2020): e64. http://dx.doi.org/10.1016/j.jvs.2020.04.118.

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13

El Khatib, N., O. Kafi, A. Sequeira, S. Simakov, Yu Vassilevski, and V. Volpert. "Mathematical modelling of atherosclerosis." Mathematical Modelling of Natural Phenomena 14, no. 6 (2019): 603. http://dx.doi.org/10.1051/mmnp/2019050.

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The review presents the state of the art in the atherosclerosis modelling. It begins with the biological introduction describing the mechanisms of chronic inflammation of artery walls characterizing the development of atherosclerosis. In particular, we present in more detail models describing this chronic inflammation as a reaction-diffusion wave with regimes of propagation depending on the level of cholesterol (LDL) and models of rolling monocytes initializing the inflammation. Further development of this disease results in the formation of atherosclerotic plaque, vessel remodelling and possible plaque rupture due its interaction with blood flow. We review plaque-flow interaction models as well as reduced models (0D and 1D) of blood flow in atherosclerotic vasculature.

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14

Marinoni, Andrea, Matteo Tamborski, Tarcisio Cerri, Gianluca Montenegro, Gianluca D’Errico, Angelo Onorati, Emanuele Piatti, and Enrico Ernesto Pisoni. "0D/1D Thermo-Fluid Dynamic Modeling Tools for the Simulation of Driving Cycles and the Optimization of IC Engine Performances and Emissions." Applied Sciences 11, no. 17 (September 1, 2021): 8125. http://dx.doi.org/10.3390/app11178125.

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The prediction of internal combustion engine performance and emissions in real driving conditions is getting more and more important due to the upcoming stricter regulations. This work aims at introducing and validating a new transient simulation methodology of an ICE coupled to a hybrid architecture vehicle, getting closer to real-time calculations. A one-dimensional computational fluid dynamic software has been used and suitably coupled to a vehicle dynamics model in a user function framework integrated within a Simulink® environment. A six-cylinder diesel engine has been modeled by means of the 1D tool and cylinder-out emissions have been compared to experimental data. The measurements available have been used also to calibrate the combustion model. The developed 1D engine model has been then used to perform driving cycle simulations considering the vehicle dynamics and the coupling with the energy storage unit in the hybrid mode. The map-based approach along with the vehicle simulation tool has also been used to perform the same simulation and the two results are compared to evaluate the accuracy of each approach. In this framework, to achieve the best simulation performance in terms of computational time over simulated time ratio, the 1D engine model has been used in a configuration with a very coarse mesh. Results have shown that despite the high mesh spacing used the accuracy of the wave dynamics prediction was not affected in a significant way, whereas a remarkable speed-up factor was achieved. This means that a crank angle resolution approach to the vehicle simulation is a viable and accurate strategy to predict the engine emission during any driving cycle with a computation effort compatible with the tight schedule of a design process.

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15

Choi, Heewon, Nam-gyu Lim, Seong Jun Lee, and Jungsoo Park. "Feasibility Study for Sustainable Use of Lithium-Ion Batteries Considering Different Positive Electrode Active Materials under Various Driving Cycles by Using Cell to Electric Vehicle (EV) Simulation." Sustainability 12, no. 22 (November 23, 2020): 9764. http://dx.doi.org/10.3390/su12229764.

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Electric vehicles have been issued to achieve sustainable mobility. Main factors to sustainable electric vehicle (EV) are that lithium-ion battery (LIB) has to maintain lower cost, lighter weight, SOC (state of charge), thermal stability, and driving ranges. In this study, nickel-cobalt-manganese (NCM), lithium iron phosphate (LFP), and lithium manganese oxide (LMO), which are used as representative positive electrode materials, were applied to battery cells. Then, the battery characteristics at the system level, according to the application of different positive electrode materials, were compared and analyzed. To this end, each of the 18650 cylindrical battery cells was modeled by applying different positive electrode active materials. The battery modeling was based on a database provided by GT(Gamma Technologies)-AutoLion. To analyze the thermal stability and capacity loss according to the temperature of the battery cell by applying different C-rate discharge and temperature conditions for each positive electrode active material, an electrochemical-based zero-dimensional (0D) analysis was performed. A test was also performed to determine the model feasibility by using a MACCOR 4300 battery charger/discharger. Moreover, a lumped battery pack modeling was performed to extend the modeled battery cell to an EV battery pack. By combining the pack and one-dimensional (1D) EV models, various driving cycles were described to investigate the battery performance at the vehicle level. It was found that the 0D electrochemistry-coupled 1D vehicle model could well predict the feasible tendencies considering various positive electrode materials of the LIB battery cell.

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16

Wang, Yan, Mingguang Yao, Xing Hua, Fei Jin, Zhen Yao, Hua Yang, Ziyang Liu, et al. "Structural Evolution of D _5h(1)-C₉₀ under High Pressure: A Mediate Allotrope of Nanocarbon from Zero-Dimensional Fullerene to One-Dimensional Nanotube." Chinese Physics Letters 39, no. 5 (May 1, 2022): 056101. http://dx.doi.org/10.1088/0256-307x/39/5/056101.

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The hybridization of fullerene and nanotube structures in newly isolated C90 with the D 5h symmetric group (D 5h (1)-C90) provides an ideal model as a mediating allotrope of nanocarbon from zero-dimensional (0D) fullerene to one-dimensional nanotube. Raman and infrared spectroscopy combined with classical molecular dynamics simulation were used to investigate the structural evolution of D 5h (1)-C90 at ambient and high pressure up to 35.1 GPa. Interestingly, the high-pressure transformations of D 5h (1)-C90 exhibit the features of both fullerene and nanotube. At around 2.5 GPa, the D 5h (1)-C90 molecule in the crystal undergoes an orientational transition to a restricted rotation. At 6.6 GPa, the tubular hexagonal part occurs and transforms into a dumbbell-like structure at higher pressure. The material starts to amorphize above 13.9 GPa, and the transition is reversible until the pressure exceeds 25 GPa. The amorphization is probably correlated with both the intermolecular bonding and the morphology change. Our results enrich our understanding of structural changes in nanocarbon from 0D to 1D.

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17

Frerichs, Jelto, and Peter Eilts. "A New Combustion Model for Medium Speed Dual-Fuel Engines in the Course of 0D/1D Simulation." Methane 1, no. 3 (July 7, 2022): 158–76. http://dx.doi.org/10.3390/methane1030013.

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In this paper, a predictive combustion model is developed and implemented in GT-Power. The model consists of a detailed physically/chemically based ignition delay model, including a 1D spray model. The spray model results at the start of combustion are used to initialize the combustion model. The spray zone and the homogenous natural gas/air mixture are burned with different combustion models, to account for the effect of the inhomogeneous fuel distribution. NOx-emissions are modelled using a standard Extended Zeldovich Mechanism, and for the HC-emissions, two flame quenching models are included and extended with an empirical correlation. The models are calibrated with measurement data from a single cylinder engine, except for the ignition delay model which needs no calibration. The start of combustion and the combustion parameters are predicted well for a wide range of injection timings and operation conditions. Furthermore, considering unburned fuel, the engine operation parameters BSFC and IMEP are also predicted satisfactory. Due to the detailed description of the different combustion phases, the influence of the injection timing on the NOx-emission is captured satisfactorily, with the standard NOx-model. Finally, the knock limited MFB50 is also predicted within an acceptable range.

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18

ISHIGAMI, Yuta, and Marie OSHIMA. "1G24 Blood flow simulation for coupling of 3D fluid-structure interaction and 1D-0D peripheral vessel model." Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME 2014.26 (2014): 225–26. http://dx.doi.org/10.1299/jsmebio.2014.26.225.

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19

Choi, Seung-Mok, Kyoung-Doug Min, and Ki-Doo Kim. "Development of 0D Multizone Combustion Model and Its Coupling with 1D Cycle-Simulation Model for Medium-Sized Direct-Injection Diesel Engine." Transactions of the Korean Society of Mechanical Engineers B 34, no. 6 (June 1, 2010): 615–22. http://dx.doi.org/10.3795/ksme-b.2010.34.6.615.

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20

Montenegro, G., A. Della Torre, A. Onorati, and R. Fairbrother. "A Nonlinear Quasi-3D Approach for the Modeling of Mufflers with Perforated Elements and Sound-Absorbing Material." Advances in Acoustics and Vibration 2013 (January 14, 2013): 1–10. http://dx.doi.org/10.1155/2013/546120.

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Increasing demands on the capabilities of engine thermo-fluid dynamic simulation and the ability to accurately predict both performance and acoustics have led to the development of several approaches, ranging from fully 3D to simplified 1D models. The quasi-3D approach is proposed as a compromise between the time-demanding 3D CFD analysis and the fast 1D approach; it allows to model the acoustics of intake and exhaust system components, used in internal combustion engines, resorting to a 3D network of 0D cells. Due to its 3D nature, the model predicts high-order modes, improving the accuracy at high frequencies with respect to conventional plane-wave approaches. The conservation equations of mass and energy are solved at cell centers, whereas the momentum equation is applied to cell connections including specific source term to account for the of sound-absorbing materials and perforated elements. The quasi-3D approach has been validated by comparing the predicted transmission loss to measured data for a number of standard configurations typical of internal combustion engine exhaust systems: a reverse-flow chamber and series chambers with perforates and resistive material.

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21

Matsuura, Sohei, Toshio Takayama, Changyoung Yuhn, Marie Oshima, Takuro Shirasu, Takafumi Akai, Toshihiko Isaji, and Katsuyuki Hoshina. "Carotid Stump Pressure and Contralateral Internal Carotid Stenosis Ratio During Carotid Endarterectomies: 1D-0D Hemodynamic Simulation of Cerebral Perfusion." Annals of Vascular Diseases 14, no. 1 (March 25, 2021): 39–45. http://dx.doi.org/10.3400/avd.oa.20-00166.

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22

Zhao, Chenxi, Zhou Li, Tianjiao Fan, Chong Xiao, and Yi Xie. "Defects Engineering with Multiple Dimensions in Thermoelectric Materials." Research 2020 (May 22, 2020): 1–23. http://dx.doi.org/10.34133/2020/9652749.

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Going through decades of development, great progress in both theory and experiment has been achieved in thermoelectric materials. With the growing enhancement in thermoelectric performance, it is also companied with the complexation of defects induced in the materials. 0D point defects, 1D linear defects, 2D planar defects, and 3D bulk defects have all been induced in thermoelectric materials for the optimization of thermoelectric performance. Considering the distinct characteristics of each type of defects, in-depth understanding of their roles in the thermoelectric transport process is of vital importance. In this paper, we classify and summarize the defect-related physical effects on both band structure and transport behavior of carriers and phonons when inducing different types of defects. Recent achievements in experimental characterization and theoretical simulation of defects are also summarized for accurately determining the type of defects serving for the design of thermoelectric materials. Finally, based on the current theoretical and experimental achievements, strategies engaged with multiple dimensional defects are reviewed for thermoelectric performance optimization.

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23

Wurzenberger, Johann C., Roland Wanker, Ales Schuemie, Reinhard Tatschl, and Johann Krammer. "OS-D1: A Simulation Framework for 0D Engine Combustion and Pollutant Formation Combined with 1D Exhaust Gas Aftertreatment : Control of Gasoline Engine Emissions During Drive-Cycle(OS-D Advanced engine simulation (prediction of performance & emissions, transient simulation),Organized Session Papers)." Proceedings of the International symposium on diagnostics and modeling of combustion in internal combustion engines 2008.7 (2008): 105–14. http://dx.doi.org/10.1299/jmsesdm.2008.7.105.

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Zhang, Yuanpeng, Marshall McDonnell, Wei Liu, and Matthew G. Tucker. "Reverse Monte Carlo modeling for low-dimensional systems." Journal of Applied Crystallography 52, no. 5 (August 29, 2019): 1035–42. http://dx.doi.org/10.1107/s160057671901080x.

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Reverse Monte Carlo (RMC) is one of the commonly used approaches for modeling total scattering data. However, to extend the capability of the RMC method for refining the structure of nanomaterials, the dimensionality and finite size need to be considered when calculating the pair distribution function (PDF). To achieve this, the simulation box must be set up to remove the periodic boundary condition in one, two or three of the dimensions. This then requires a correction to be applied for the difference in number density between the real system and the simulation box. In certain circumstances an analytical correction for the uncorrelated pairings of atoms is also applied. The validity and applicability of our methodology is demonstrated by applying the algorithms to simulate the PDF patterns of carbon systems with various dimensions, and also by using them to fit experimental data of CuO nanoparticles. This alternative approach for characterizing the local structure of nano-systems with the total scattering technique will be made available via the RMCProfile package. The theoretical formulation and detailed explanation of the analytical corrections for low-dimensional systems – 2D nanosheets, 1D nanowires and 0D nanoparticles – is also given.

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25

Champagne, Aurélie, Samuel Dechamps, Simon M. M. Dubois, Aurélien Lherbier, Viet-Hung Nguyen, and Jean-Christophe Charlier. "Computational Atomistic Modeling in Carbon Flatland and Other 2D Nanomaterials." Applied Sciences 10, no. 5 (March 3, 2020): 1724. http://dx.doi.org/10.3390/app10051724.

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As in many countries, the rise of nanosciences in Belgium has been triggered in the eighties in the one hand, by the development of scanning tunneling and atomic force microscopes offering an unprecedented possibility to visualize and manipulate the atoms, and in the other hand, by the synthesis of nano-objects in particular carbon nanostructures such as fullerene and nanotubes. Concomitantly, the increasing calculating power and the emergence of computing facilities together with the development of DFT-based ab initio softwares have brought to nanosciences field powerful simulation tools to analyse and predict properties of nano-objects. Starting with 0D and 1D nanostructures, the floor is now occupied by the 2D materials with graphene being the bow of this 2D ship. In this review article, some specific examples of 2D systems has been chosen to illustrate how not only density functional theory (DFT) but also tight-binding (TB) techniques can be daily used to investigate theoretically the electronic, phononic, magnetic, and transport properties of these atomically thin layered materials.

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26

Tadros, Mina, Manuel Ventura, and C. Guedes Soares. "Optimization of the Performance of Marine Diesel Engines to Minimize the Formation of SOx Emissions." Journal of Marine Science and Application 19, no. 3 (September 2020): 473–84. http://dx.doi.org/10.1007/s11804-020-00156-0.

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Abstract Optimization procedures are required to minimize the amount of fuel consumption and exhaust emissions from marine engines. This study discusses the procedures to optimize the performance of any marine engine implemented in a 0D/1D numerical model in order to achieve lower values of exhaust emissions. From that point, an extension of previous simulation researches is presented to calculate the amount of SOx emissions from two marine diesel engines along their load diagrams based on the percentage of sulfur in the marine fuel used. The variations of SOx emissions are computed in g/kW·h and in parts per million (ppm) as functions of the optimized parameters: brake specific fuel consumption and the amount of air-fuel ratio respectively. Then, a surrogate model-based response surface methodology is used to generate polynomial equations to estimate the amount of SOx emissions as functions of engine speed and load. These developed non-dimensional equations can be further used directly to assess the value of SOx emissions for different percentages of sulfur of the selected or similar engines to be used in different marine applications.

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27

Zhang, Hao, Naoya Fujiwara, Masaharu Kobayashi, Shigeki Yamada, Fuyou Liang, Shu Takagi, and Marie Oshima. "Development of a Numerical Method for Patient-Specific Cerebral Circulation Using 1D–0D Simulation of the Entire Cardiovascular System with SPECT Data." Annals of Biomedical Engineering 44, no. 8 (December 31, 2015): 2351–63. http://dx.doi.org/10.1007/s10439-015-1544-8.

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28

Wanker, Roland J., Johann C. Wurzenberger, and Henrik A. Schuemie. "Three-Way Catalyst Light-off During the NEDC Test Cycle: Fully Coupled 0D/1D Simulation of Gasoline Combustion, Pollutant Formation and Aftertreatment Systems." SAE International Journal of Fuels and Lubricants 1, no. 1 (June 23, 2008): 1373–86. http://dx.doi.org/10.4271/2008-01-1755.

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29

Zhu, Yichuan, Zenon Medina-Cetina, and Alma Rosa Pineda-Contreras. "Spatio-Temporal Statistical Characterization of Boundary Kinematic Phenomena of Triaxial Sand Specimens." Materials 15, no. 6 (March 16, 2022): 2189. http://dx.doi.org/10.3390/ma15062189.

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This paper follows up on a reference paper that inspired MDPI’s Topic “Stochastic Geomechanics: From Experimentation to Forward Modeling”, where global and local deformation effects on sand specimens are fully described from high resolution boundary displacement fields, and supported by its experimental database, which is open to the scientific community for further study. This paper introduces the use of spatio-temporal statistics from a subset of such an experimental database to characterize the specimens’ spatio-temporal displacement fields, populated by repeating a set of triaxial compression tests on drained, dry, vacuum-consolidated sand specimens, tested under similar experimentally controlled conditions. A three-dimensional digital image correlation (3D-DIC) technique was used to measure the specimens’ boundary displacement fields throughout the course of shearing under axial compression. Spatio-temporal first- and second-order statistics were computed for different data dimensionality conditions (0D, 0D-T, 1D-T, 3D-T) to identify and characterize the dominant failure mechanisms across different testing specimens. This allowed us to quantify localization phenomena’s spatio-temporal uncertainty. Results show that the uncertainty captured along the deformation process across different dimensionality conditions can be directly associated with different failure mechanisms, including localization patterns, such as the onset and evolution of shear, compression, and expansion bands. These spatio-temporal observations show the dependencies between locally distinctive displacement regions over a specimen’s surface, and across different times during a specimen’s shearing process. Results of this work provide boundary spatio-temporal statistics of experimental evidence in sands, which sets the basis for the development of research on the numerical simulation of sand’s constitutive behavior. Moreover, it allows to add a new understanding on the effect of uncertainty on the mechanistic interpretation of sands’ kinematic phenomena.

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Bianchi, Fiammetta Rita, Barbara Bosio, Arianna Baldinelli, and Linda Barelli. "Optimization of a Reference Kinetic Model for Solid Oxide Fuel Cells." Catalysts 10, no. 1 (January 10, 2020): 104. http://dx.doi.org/10.3390/catal10010104.

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Solid oxide fuel cells (SOFCs) stand out among other fuel cell types because of their specific characteristics. The high operating temperature permits to reach optimal conductivity and favours kinetics without requiring noble metal catalysts. The SOFC behaviour analysis is fundamental to optimise operating conditions and to obtain the best performance. For this purpose, specific models are studied to investigate the electrochemical kinetics, which is the most critical aspect in the simulation. This is closely linked to cell materials and structure, as well as to operating conditions (feed composition and temperature above all) that influence cell polarization effects. The present work aims at evaluating these contributions by means of a semi-empirical kinetic formulation based on both theoretical and experimental approaches. A dedicated experimental campaign on an anode-supported NiYSZ/8YSZ/GDC-LSCF button cell is performed to identify experimental parameters. Each working variable is changed singularly to understand its specific effect, avoiding the overlap of multiple effects. The studied kinetics is validated using a 0D model to evaluate global cell operation, and a 1D model to estimate occurring mechanisms along anode thickness. The comparison between experimental and simulated data allows a preliminary validation of the proposed model, providing a base for subsequent more specific studies.

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Di Lorenzo, Giuseppe, Emma Frosina, Luigi De Petrillo, Davide Lauria, Adolfo Senatore, Francesco Curreri, Guido Saccone, Marcello Kivel Mazuy, and Ciro Pascarella. "Design and Development of Hybrid-Electric Propulsion Model for Aeronautics." MATEC Web of Conferences 304 (2019): 03012. http://dx.doi.org/10.1051/matecconf/201930403012.

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Nowadays, worldwide environmental issue, associated to reduction of pollutant and greenhouse emissions are gaining considerable attention. Aviation sector contribution to the whole CO2 released accounts to around 2%, but it is expected to grow in the next future due to increase of demand. Probably, combustion engine design and fuel efficiency have already reached their optimum technology level and only a breakthrough as hybrid-electric propulsion could be able to satisfy the new international more demanding requirements. However, an improvement of the technology readiness level of hybrid-electric propulsion is strongly necessary and many operational and safety challenges should be addressed. In the work here reported, a hybrid-electric model was designed and developed for general aviation aircrafts, by means of the Mathworks® Matlab – Simulink 1D/0D simulation environment. Both thermal and electric energy storage units, transmission systems and power management devices were considered and the overall performances were evaluated during cruise phase and a conventional training mission, characterized by several run(lap) “touch-and-go”. Furthermore, an innovative mathematical methodology was implemented for battery pack discharge profile interpolation. Finally, reliability and accuracy of the new proposed model were evaluated through comparison with the commercial code Simcenter AMESim® software and an average bias only equal to 5% was achieved.

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Irimescu, Adrian, Bianca Maria Vaglieco, Simona Silvia Merola, Vasco Zollo, and Raffaele De Marinis. "Conversion of a Small-Size Passenger Car to Hydrogen Fueling: Simulation of CCV and Evaluation of Cylinder Imbalance." Machines 11, no. 2 (January 19, 2023): 135. http://dx.doi.org/10.3390/machines11020135.

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In the efforts to achieve zero-emission transportation, hydrogen offers a valid choice as a complete replacement of gasoline. Adapting spark ignition (SI) engines to this alternative fuel can be implemented with relatively minor changes and limited investment in added components. The conversion of a small-size passenger car to hydrogen fueling was evaluated initially from the perspective of achievable range and peak power. Overall, the concept was found to be feasible and comparable to the fully electric version of the vehicle. Cylinder imbalance was found to be one of the possible issues compared to gasoline operation. This study looks in more detail at cycle-to-cycle variability (CCV) and how this could influence vehicle dynamics as well as noise–harshness–vibration (NHV). CCV was simulated with a 0D/1D approach in vehicle-relevant engine speed–load conditions. A dedicated laminar flame speed sub-model was implemented so as to include fuel chemistry effects, while CCV was simulated by inducing perturbations in the initial combustion stages and fuel system characteristics as well as variation of air–fuel ratio throughout flame propagation. Significant improvement of stability was predicted with hydrogen, while cylinder imbalance was found to be one of the main sources of variability. Applying algorithms that compensate for the imbalance through individual injection valve regulation may not be enough to mitigate the identified issue, and more extensive changes of control strategies could be required. The start of injection settings may need to be adapted for each operating condition to maximize the effect of H2 combustion stabilization.

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Zheng, Yunxin, Zhiping Hu, Xiang Ren, Rui Wang, Enxiang Zhang, and Zhao Long. "Effects of Partial Supporting Pile Removal from Deep Foundation Pits by Shallow Excavation Method in Loess Areas." Advances in Materials Science and Engineering 2021 (August 27, 2021): 1–13. http://dx.doi.org/10.1155/2021/9934113.

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Partial supporting piles removal from deep foundation pit may lead to large-scale foundation pit collapse, resulting in severe consequences. Various studies have investigated the underpinning technology of cutting abutment piles by combining field monitoring and numerical simulation, but there are few studies on cutting supporting piles of foundation pit by the shallow excavation method. Taking an actual deep and large foundation pit as an example, the finite element method (FEM) was adopted to study the surface settlement and the changing trend of the force and displacement of the supporting pile caused by cutting piles during the shallow excavation of double tunnels. The FEM results were verified with the field monitoring data. The simulation results show that the surface settlement around the foundation pit mainly occurs at the pile cutting stage under different excavation sequences (0D, 1D, 2D), and the main distribution area is the one-fold diameter area outside the double tunnel. After the supporting piles are partially cut, the bending moment and displacement of the lower part of the broken piles differ significantly due to different excavation sequences, but the bending moment and displacement of the upper part of the broken piles are basically similar. In the process of removing the supporting piles, the Earth pressure behind the piles is redistributed, and the load is mainly transferred to the adjacent supporting piles outside the tunnel within the radius of one time of the tunnel diameter. However, the load is not evenly transferred to the adjacent supporting piles. Some recommendations for the reinforcement scheme of the supporting structure during cutting supporting piles in deep foundation pit are also proposed. The research results can provide theoretical basis and practical guidance for the construction of similar projects in the future.

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Moridis, George, Niwit Anantraksakul, and Thomas A. Blasingame. "The Partial Transformational Decomposition Method for a Hybrid Analytical/Numerical Solution of the 3D Gas-Flow Problem in a Hydraulically Fractured Ultralow-Permeability Reservoir." SPE Journal 26, no. 04 (February 24, 2021): 2440–67. http://dx.doi.org/10.2118/199015-pa.

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Summary The analysis of gas production from fractured ultralow-permeability (ULP) reservoirs is most often accomplished using numerical simulation, which requires large 3D grids, many inputs, and typically long execution times. We propose a new hybrid analytical/numerical method that reduces the 3D equation of gas flow into either a simple ordinary-differential equation (ODE) in time or a 1D partial-differential equation (PDE) in space and time without compromising the strong nonlinearity of the gas-flow relation, thus vastly decreasing the size of the simulation problem and the execution time. We first expand the concept of pseudopressure of Al-Hussainy et al. (1966) to account for the pressure dependence of permeability and Klinkenberg effects, and we also expand the corresponding gas-flow equation to account for Langmuir sorption. In the proposed hybrid partial transformational decomposition method (TDM) (PTDM), successive finite cosine transforms (FCTs) are applied to the expanded, pseudopressure-based 3D diffusivity equation of gas flow, leading to the elimination of the corresponding physical dimensions. For production under a constant- or time-variable rate (q) regime, three levels of FCTs yield a first-order ODE in time. For production under a constant- or time-variable pressure (pwf) regime, two levels of FCTs lead to a 1D second-order PDE in space and time. The fully implicit numerical solutions for the FCT-based equations in the multitransformed spaces are inverted, providing solutions that are analytical in 2D or 3D and account for the nonlinearity of gas flow. The PTDM solution was coded in a FORTRAN95 program that used the Laplace-transform (LT) analytical solution for the q-problem and a finite-difference method for the pwf problem in their respective multitransformed spaces. Using a 3D stencil (the minimum repeatable element in the horizontal well and hydraulically fractured system), solutions over an extended production time and a substantial pressure drop were obtained for a range of isotropic and anisotropic matrix and fracture properties, constant and time-variable Q and pwf production schemes, combinations of stimulated-reservoir-volume (SRV) and non-SRV subdomains, sorbing and nonsorbing gases of different compositions and at different temperatures, Klinkenberg effects, and the dependence of matrix permeability on porosity. The limits of applicability of PTDM were also explored. The results were compared with the numerical solutions from a widely used, fully implicit 3D simulator that involved a finely discretized (high-definition) 3D domain involving 220,000 elements and show that the PTDM solutions can provide accurate results for long times for large well drawdowns even under challenging conditions. Of the two versions of PTDM, the PTD-1D was by far the better option and its solutions were shown to be in very good agreement with the full numerical solutions, while requiring a fraction of the memory and orders-of-magnitude lower execution times because these solutions require discretization of only the time domain and a single axis (instead of three). The PTD-0D method was slower than PTD-1D (but still much faster than the numerical solution), and although its solutions were accurate for t < 6 months, these solutions deteriorated beyond that point. The PTDM is an entirely new approach to the analysis of gas flow in hydraulically fractured ULP reservoirs. The PTDM solutions preserve the strong nonlinearity of the gas-flow equation and are analytical in 2D or 3D. This being a semianalytical approach, it needs very limited input data and requires computer storage and computational times that are orders-of-magnitude smaller than those in conventional (numerical) simulators because its discretization is limited to time and (possibly) a single spatial dimension.

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Laroche, Emmanuel, David Donjat, and Philippe Reulet. "A Combined Experimental and Numerical Characterization of the Flowfield and Heat Transfer around a Multiperforated Plate with Compound Angle Injection." Energies 14, no. 3 (January 26, 2021): 613. http://dx.doi.org/10.3390/en14030613.

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The aerodynamic and thermal behaviour of multiperforated zones in combustors is essential to the development of future combustion chambers. Detailed databases are therefore crucial for the validation of RANS/LES solvers, but also regarding the derivation of heat transfer correlations used in 0D/1D in-house codes developed by engine manufacturers. In the framework of FP7 EU SOPRANO Program, the test-rig used in a previous study is modified to be compatible with anisothermal conditions. The plate studied is a 12:1 model with a 90∘ compound angle injection. A heating system is used to generate a moderate temperature gradient of about 20 K between the secondary hot flow and the main cold flow. The aerodynamic field is acquired by a PIV 2D-3C (Stereo Particle Image Velocimetry) system. The surface heat transfer coefficient is derived based on surface temperature distribution acquisitions. Several heating power levels are tested, which allows evaluating the convective heat transfer coefficient and reference temperature through a linear regression. Measurements are conducted on both sides of the plate, which also gives access to those quantities on the injection/suction sides. From a numerical point of view, the configuration is studied using the unstructured ONERA in-house CEDRE solver with an advanced Reynolds Stress Model. A systematic comparison is presented between the experimental and numerical database. Due to the high blowing ratio, the film protection is low in the first rows, with a convective heat transfer coefficient enhancement around three, and freestream cold air brought close to the wall by vortices created at injection. After four rows, the film is building up, leading gradually to a better insulation of the wall. The comparison with the numerical simulation exhibits a qualitative agreement on the main flow structures. However, the mixing between the jets, the film and the freestream is underestimated by the calculation.

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Kroon, Wilco, Wouter Huberts, Marielle Bosboom, and Frans van de Vosse. "A Numerical Method of Reduced Complexity for Simulating Vascular Hemodynamics Using Coupled 0D Lumped and 1D Wave Propagation Models." Computational and Mathematical Methods in Medicine 2012 (2012): 1–10. http://dx.doi.org/10.1155/2012/156094.

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A computational method of reduced complexity is developed for simulating vascular hemodynamics by combination of one-dimensional (1D) wave propagation models for the blood vessels with zero-dimensional (0D) lumped models for the microcirculation. Despite the reduced dimension, current algorithms used to solve the model equations and simulate pressure and flow are rather complex, thereby limiting acceptance in the medical field. This complexity mainly arises from the methods used to combine the 1D and the 0D model equations. In this paper a numerical method is presented that no longer requires additional coupling methods and enables random combinations of 1D and 0D models using pressure as only state variable. The method is applied to a vascular tree consisting of 60 major arteries in the body and the head. Simulated results are realistic. The numerical method is stable and shows good convergence.

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Ji, Bingxue, Nan Chen, Changxiang Shao, Qianwen Liu, Jian Gao, Tong Xu, Huhu Cheng, and Liangti Qu. "Intelligent multiple-liquid evaporation power generation platform using distinctive Jaboticaba-like carbon nanosphere@TiO2 nanowires." Journal of Materials Chemistry A 7, no. 12 (2019): 6766–72. http://dx.doi.org/10.1039/c8ta12328d.

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38

BATTISTA, CHRISTINA, DANIEL BIA, YANINA ZÓCALO GERMÁN, RICARDO L. ARMENTANO, MANSOOR A. HAIDER, and METTE S. OLUFSEN. "WAVE PROPAGATION IN A 1D FLUID DYNAMICS MODEL USING PRESSURE-AREA MEASUREMENTS FROM OVINE ARTERIES." Journal of Mechanics in Medicine and Biology 16, no. 02 (March 2016): 1650007. http://dx.doi.org/10.1142/s021951941650007x.

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This study considers a 1D fluid dynamics arterial network model with 14 vessels developed to assimilate ex vivo 0D temporal data for pressure-area dynamics in individual vessel segments from 11 male Merino sheep. A 0D model was used to estimate vessel wall parameters in a two-parameter elastic model and a four-parameter Kelvin viscoelastic model. This was done using nonlinear optimization minimizing the least squares error between model predictions and measured cross-sectional areas. Subsequently, estimated values for elastic stiffness and unstressed area were related to construct a nonlinear relationship. This relation was used in the network model. A 1D single vessel model of the aorta was then developed and used to estimate the inflow profile and parameters for total resistance and compliance for the downstream network and to demonstrate effects of incorporating viscoelasticity in the arterial wall. Lastly, the extent to which vessel wall parameters estimated from ex vivo data can be used to realistically simulate pressure and area in a vessel network was evaluated. Elastic wall parameters in the network simulations were found to yield pressure-area relationships across all vessel locations and sheep that were in ranges comparable to those in the ex vivo data.

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Giardiello, Giovanni, Alfredo Gimelli, and Francesco de Nola. "Engine Valvetrain Lift Prediction Using a Physic-based Model for The Electronic Control Unit Calibration." E3S Web of Conferences 197 (2020): 06015. http://dx.doi.org/10.1051/e3sconf/202019706015.

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The electronic control has an increasingly important role in the evolution of the internal combustion engine (ICE) and the vehicle. Research in the automotive sector, in this historical period, is dictated by three main guidelines: reducing polluting emissions and fuel consumption while maintaining high performance. The Electronic Control Unit (ECU) has made it possible, complicating the engine both in terms of architecture and in terms of strategies, controlling, through simplified functions, physical phenomena in an ever more precise way. The ECU functions are experimentally calibrated, reducing the error between the quantity estimated by the function and the experimental quantity over the entire operating range of the engine, developing extensive experimental campaigns. The calibration process of the ECU functions is one of the longest and most expensive processes in the development of a new vehicle. Some lines of research have been explored to reduce the experimental tests to be carried out on the test bench. The use of neural networks (NN) has proven to be effective, leading to a reduction in experimental tests from 40 to 60%. Another methodology consists in the use of 1D/0D Thermo-fluid dynamic models of the ICE. These models are used as virtual test benches and through them it is possible to carry out the experimental campaigns necessary for the calibration of the control unit functions. At the real test bench, only the few experimental tests necessary for the validation of the model must be carried out. One of the simplifications that is usually made in the 1D/0D ICE models consists in assigning a single intake and exhaust valve lift, without taking into account the effect of the engine speed on the valve lift in early intake valve closure (EIVC) mode for engines equipped with VVA. This phenomenon has a not negligible effect on engine performance, especially at high engine speeds. In the case of engine models equipped with VVA, the valve lift cannot be imposed, since it is unique for each closing angle at each engine speed. Indeed, in order to assign the correct valve lift for a given engine speed and EIVC, numerous experimental tests should be carried out, making vain the beneficial effects of the method. In this work, the authors propose the use of a 0D/1D CFD model of the entire electro-hydraulic valvetrain VVA module, coupled with 1D lumped mass for reproducing the linear displacements of the intake valve, and for simulating the interactions between flow and mechanical systems of the solenoid hydro-mechanical valve. Thus, model simulations allow to predict the valve lift in all the necessary conditions in the experimental campaigns for the calibration of the control unit functions. Starting from geometric valvetrain data, the model has been validated with a parametric analysis of some variables on which there was greater uncertainty, by comparing the valve lift obtained by the model with the experimental ones in certain engine speeds. Subsequently, the authors have obtained the valve lifts in conditions not used for model validation, comparing them with their respective experimental lifts. The model has proven to be sensitive to the effect of the variation of the engine speed, reproducing the valve lift with a low error. In this way it is possible to reduce the experimental effort aimed to the calibration process considering that the virtual experimental campaign has proven to be reliable.

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Bock, Josué, Jan Kaiser, Max Thomas, Andreas Bott, and Roland von Glasow. "A description of the first open-source community release of MISTRA-v9.0: a 0D/1D atmospheric boundary layer chemistry model." Geoscientific Model Development 15, no. 14 (July 27, 2022): 5807–28. http://dx.doi.org/10.5194/gmd-15-5807-2022.

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Abstract. We present MISTRA-v9.0, a one-dimensional (1D) and box (0D) atmospheric chemistry model. The model includes a detailed particle description with regards to the microphysics, gas–particle interactions, and liquid-phase chemistry within particles. Version 9.0 (v9.0) is the first release of MISTRA as an open-source community model. A major review of the code has been performed along with this public version release to improve the user friendliness and platform independence of the model. The purpose of this public release is to maximise the benefit of MISTRA to the community by making the model freely available and easier to use and develop. This paper presents a thorough description of the model characteristics and components. We show some examples of simulations reproducing previous studies with MISTRA, finding that v9.0 is consistent with previous versions.

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Kovacs, Laszlo, and Szilard Szabo. "Comparative study on the improvement of the gas exchange process efficiency of a high speed IC engine using swinging valve." Analecta Technica Szegedinensia 13, no. 2 (December 3, 2019): 28–37. http://dx.doi.org/10.14232/analecta.2019.2.28-37.

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Using poppet valves to control the air-fuel mixture entering and leaving the combustion chamber of an engine is just one among many other more flow efficient alternative solution. The geometry of the poppet valve and its valve seat are the main causes of the flow restriction in the internal combustion engines. The engine downsizing concept dictates to obtain more power from a given engine volume, therefore proportionally more air should be drawn into the cylinders to burn more fuel. These criteria best fulfilled with a new Swinging Valve (SwV) solution that enables the unhindered flow of air and exhaust gas through an engine’s cylinder. The filling of a cylinder is improved while the pumping losses are decreased. In this experiment, a Super Flow SF600 flow bench was used to examine a Suzuki SV650 motorcycle engine’s normal poppet valve cylinder head and a Swinging Valve cylinder head was constructed as well. First the flow parameters of the original cylinder head were obtained then the Swinging Valve head was investigated in the same way. The outcomes of the tests show the superiority of the new concept. The results will also be the base of further 0D/1D engine simulations.

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Cecere, Giovanni, Adrian Irimescu, and Simona Silvia Merola. "Design of an Optically Accessible Intake Manifold for Characterization of Liquid and Gaseous Jets in PFI Operating Conditions." Designs 7, no. 1 (February 1, 2023): 24. http://dx.doi.org/10.3390/designs7010024.

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The intake manifold and its components play a key role in the proper formation of air–fuel mixtures suitable for correct engine operation. In this article, starting from the original intake manifold design fitted to an optically accessible spark-ignited engine, a new solution was developed so as to allow the application of high-speed imaging of the fuel jet located between the runner and intake valves (Port Fuel Injection). To compare the two designs in terms of overall engine performance parameters such as volumetric efficiency, 0D/1D simulations were performed in motored conditions. Measurements at different crankshaft speed values were used for calibrating the intake line parameters and providing boundary conditions. Finite Element Analysis (FEM) was performed in SolidWorks to verify the structural strength of the new design when operating in the most critical conditions, i.e., boosted operation. As an overall conclusion, the results show that the new design guarantees a wider range of intake pressure values during the intake stroke, thus expanding the possible operative points. This can be obtained without compromising structural integrity, given that predicted safety factors were well above acceptable limits even for relatively high boost levels.

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Broatch, Alberto, Pablo Olmeda, Pau Bares, and Sebastián Aceros. "Integral Thermal Management Studies in Winter Conditions with a Global Model of a Battery-Powered Electric Bus." Energies 16, no. 1 (December 23, 2022): 168. http://dx.doi.org/10.3390/en16010168.

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The potential of e-bus transportation to improve air quality and reduce noise pollution in cities is significant. In order to improve efficiency and extend the useful life of these vehicles, there is a growing need to investigate improvements for the thermal management system of electric city buses. In electric vehicles, there are several systems whose thermal behaviors need to be regulated, such as batteries, electric machines, power electronics, air conditioning, and cabin. In this study, a 0D/1D model of an electric city bus is developed that integrates all sub-models of the powertrain, auxiliaries, and thermal management system. This model is used to evaluate different configurations and thermal management strategies of the electric urban bus by simulating public transport driving cycles in Valencia, Spain, under winter conditions. First, the original thermal–hydraulic circuit of the bus was modified, resulting in an improvement in the battery energy consumption with savings of 11.4% taking advantage of the heat produced in the electric motors to heat the battery. Then, the original PTC heating system of the bus was compared with a proposed heat pump system in terms of battery power consumption. The heat pump system achieved an energy savings of 3.9% compared to the PTC heating system.

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Ross, Molly, and Hitesh Bindra. "Statistical Mechanics-Based Surrogates for Scalar Transport in Channel Flow." Fluids 6, no. 2 (February 10, 2021): 79. http://dx.doi.org/10.3390/fluids6020079.

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Thermal hydraulics, in certain components of nuclear reactor systems, involve complex flow scenarios, such as flows assisted by free jets and stratified flows leading to turbulent mixing and thermal fluctuations. These complex flow patterns and thermal fluctuations can be extremely critical from a reactor safety standpoint. The component-level lumped approximations (0D) or one-dimensional approximations (1D) models for such components and subsystems in safety analysis codes cannot capture the physics accurately, and may introduce a large degree of modeling uncertainty. On the other hand, high-fidelity computational fluid dynamics codes, which provide numerical solutions to the Navier–Stokes equations, are accurate but computationally intensive, and thus cannot be used for system-wide analysis. An alternate way to improve reactor safety analysis is by building reduced-order emulators from computational fluid dynamics (CFD) codes to improve system scale models. One of the key challenges in developing a reduced-order emulator is to preserve turbulent mixing and thermal fluctuations across different-length scales or time-scales. This paper presents the development of a reduced-order, non-linear, “Markovian” statistical surrogate for turbulent mixing and scalar transport. The method and its implementation are demonstrated on a canonical problem of differentially heated channel flow, and high-resolution direct numerical simulations (DNS) data are used for emulator or surrogate development. This statistical surrogate model relies on Kramers–Moyal expansion and emulates the turbulent velocity signal with a high degree of accuracy.

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D’Arco, M., G. Giardiello, M. Baratta, F. de Nola, A. Gimelli, and D. Misul. "Modeling of an Organic Rankine Cycle Waste Heat Recovery system for automotive engine applications." E3S Web of Conferences 312 (2021): 07014. http://dx.doi.org/10.1051/e3sconf/202131207014.

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The remarkable investments made by manufacturers over the last few decades have contributed to improving the performance of internal combustion engines in every aspect: lower polluting emissions, greater specific power and thermal efficiency. Despite this, on an average, about 40% of the thermal power theoretically available from the combustion of the fuel is still stored in the exhaust gases and therefore dispersed in the environment. In this work the modeling and validation of a waste heat recovery (WHR) plant will be described, combining the engine with a low temperature Organic Rankine Cycle (ORC) system, in order to investigate the feasibility of this system on board of a vehicle, analyzing the quantity of thermal power recovered and made available in the form of electrical power. The ORC plant is modeled using a 0D/1D thermo-fluid dynamic approach. Starting from experimental tests, a map-based model for the piston pump and the scroll expander has been developed. The model has been validated through the use of a vector optimization technique, exploiting a genetic algorithm (MOGA). Subsequently, this system has been coupled to a spark ignition engine for automotive applications, adapting its speed range to comply with the ORC experimental tests. To have an accurate control over the expander inlet temperature, a bypass circuit and two throttles actuated by a PI controller have been implemented. The simulations were performed by considering 18 engine points at maximum load and different rpm. An average thermal efficiency increase of the system of 2.6% was obtained by introducing the recovery plant, and wide improvement chance can be foreseen in the case of ORC full-power use.

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Larbi, T., I. Toumi, K. Doll, and M. Amlouk. "Assessing the structural stability and vibration properties in beryllium selenide from the (3D) bulk, the (0D) molecule, the (2D) monolayer to the (1D) single walled nanotubes through ab initio simulations." Surfaces and Interfaces 24 (June 2021): 101087. http://dx.doi.org/10.1016/j.surfin.2021.101087.

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Desantes, José M., Ricardo Novella, Luis M. García-Cuevas, and Marcos Lopez-Juarez. "Feasibility Study for a Fuel Cell-Powered Unmanned Aerial Vehicle with a 75 Kg Payload." Transactions on Aerospace Research 2022, no. 2 (June 1, 2022): 13–30. http://dx.doi.org/10.2478/tar-2022-0008.

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Abstract Among the possible electric powerplants currently driving low-payload UAVs (up to around 10 kg of payload), batteries offer certain clear benefits, but for medium-payload operation such as aerotaxis and heavy-cargo transportation UAVs, battery capacity requirements restrict their usage due to high weight and volume. In light of this situation, fuel cell (FC) systems (FCS) offer clear benefits over batteries for the medium-payload UAV segment (> 50 kg). Nevertheless, studies regarding the application of FCS powerplants to this UAV segment are limited and the in-flight performance has not been clearly analysed. In order to address this knowledge gap, a feasibility analysis of these particular applications powered by FCS is performed in this study. A validated FC stack model (40 kW of maximum power) was integrated into a balance of plant to conform an FCS. As a novelty, the management of the FCS was optimized to maximize the FCS efficiency at different altitudes up to 12500 ft, so that the operation always implies the lowest H2 consumption regardless of the altitude. In parallel, an UAV numerical model was developed based on the ATLANTE vehicle and characterized by calculating the aerodynamic coefficients through CFD simulations. Then, both models were integrated into a 0D-1D modelling platform together with an energy management strategy optimizer algorithm and a suitable propeller model. With the preliminary results obtained from the FCS and UAV models, it was possible to ascertain the range and endurance of the vehicle. As a result, it was concluded that the combination of both technologies could offer a range over 600 km and an endurance over 5 h. Finally, with the integrated UAV-FCS model, a flight profile describing a medium altitude, medium endurance mission was designed and used to analyse the viability of FC-powered UAV. The results showed how UAVs powered by FCS are viable for the considered aircraft segment, providing competitive values of specific range and endurance.

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48

Ghitti, Beatrice, Lucas Omar Müller, and Eleuterio Francisco Toro. "Nonlinear lumped-parameter models for blood flow simulations in networks of vessels." ESAIM: Mathematical Modelling and Numerical Analysis, May 31, 2022. http://dx.doi.org/10.1051/m2an/2022052.

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To address the issue of computational efficiency related to the modelling of blood flow in complex networks, we derive a family of nonlinear lumped-parameter models for blood flow in compliant vessels departing from a well-established one-dimensional model. These 0D models must preserve important nonlinear properties of the original 1D model: the nonlinearity of the pressure-area relation and the pressure-dependent parameters characterizing the 0D models, the resistance R and the inductance L , defined in terms of a time-dependent cross-sectional area subject to pressure changes. We introduce suitable coupling conditions to join 0D vessels through 0D junctions and construct 0D networks preserving the original 1D network topology. The newly derived nonlinear 0D models are then applied to several arterial networks and the predicted results are compared against (i) the reference 1D results, to validate the models and assess their ability to reproduce good approximations of pressure and flow waveforms in all vessels at a much lower computational cost, measured in terms of CPU time, and (ii) the linear 0D results, to evaluate the improvement gained by including certain nonlinearities in the 0D models, in terms of agreement with the 1D results.

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49

Marinoni, Andrea Massimo, Angelo Onorati, Gianluca Montenegro, Lorenzo Sforza, Tarcisio Cerri, Pablo Olmeda, and Amin Dreif. "RDE cycle simulation by 0D/1D models to investigate IC engine performance and cylinder-out emissions." International Journal of Engine Research, December 22, 2022, 146808742211419. http://dx.doi.org/10.1177/14680874221141936.

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In this work, the development and application of advanced predictive 0D/1D methodologies to simulate Real Driving Emission (RDE) cycles are described. Firstly, the 1D simulation model is validated on a map of steady state operating points, which allows to use successively the very same model, with its calibration, during an RDE cycle simulation, considering the sequence of varying loads, and rotational speeds. In particular, the validated 1D model is used to simulate a typical RDE transient cycle of approximately 1 h and 45 min. The test case investigated is a modern plug-in hybrid passenger car engine, in which the thermal power unit consists of a 1 L three-cylinder, turbocharged gasoline engine. The experimental and simulated RDE cycle is characterized by a sensibly varying Internal Combustion Engine (ICE) operation, allowing to evaluate engine performance and cylinder out emissions. To speed up the calculation and significantly lower the Central Processing Unit (CPU)/real time ratio a dedicated numerical solver for fast simulation has been implemented and tested, while keeping the fidelity of the results. A predictive 0D, multi-zone model for Spark Ignition (SI) combustion has been applied, together with emission sub-models for the calculation of the main pollutants. Both instantaneous and cumulative emissions have been evaluated. The results of the simulations have been compared to the experimental data of RDE cycles, showing a good predictiveness of the models and the high potential of 0D/1D simulation codes as design tools, in the new scenario of demanding testing procedures. This approach can be applied for any engine configuration operating under any transient condition.

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50

Gu, Shenghao, Weiliang Wen, Tianjun Xu, Xianju Lu, Zetao Yu, Xinyu Guo, and Chunjiang Zhao. "Use of 3D modeling to refine predictions of canopy light utilization: A comparative study on canopy photosynthesis models with different dimensions." Frontiers in Plant Science 13 (August 18, 2022). http://dx.doi.org/10.3389/fpls.2022.735981.

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Canopy photosynthesis integrates leaf functional and structural traits in space and time and correlates positively with yield formation. Many models with different levels of architectural details ranging from zero-dimensional (0D) to three-dimensional (3D) have been developed to simulate canopy light interception and photosynthesis. Based on these models, a crop growth model can be used to assess crop yield in response to genetic improvement, optimized practices, and environmental change. However, to what extent do architectural details influence light interception, photosynthetic production, and grain yield remains unknown. Here, we show that a crop growth model with high-resolution upscaling approach in space reduces the departure of predicted yield from actual yield and refines the simulation of canopy photosynthetic production. We found crop yield predictions decreased by 12.0–48.5% with increasing the resolution of light simulation, suggesting that a crop growth model without architectural details may result in a considerable departure from the actual photosynthetic production. A dramatic difference in light interception and photosynthetic production of canopy between cultivars was captured by the proposed 3D model rather than the 0D, 1D, and 2D models. Furthermore, we found that the overestimation of crop yield by the 0D model is caused by the overestimation of canopy photosynthetically active radiation (PAR) interception and the RUE and that by the 1D and 2D model is caused by the overestimated canopy photosynthesis rate that is possibly related to higher predicted PAR and fraction of sunlit leaves. Overall, this study confirms the necessity of taking detailed architecture traits into consideration when evaluating the strategies of genetic improvement and canopy configuration in improving crop yield by crop modeling.

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