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Jia, Yun Fei, i De Ren Kong. "A Study on Measurement Uncertainty of a Vortex Flow Meter in Discrete Liquid Phase". Advanced Materials Research 346 (wrzesień 2011): 593–99. http://dx.doi.org/10.4028/www.scientific.net/amr.346.593.
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The measurement uncertainty of vortex flowmeter was examined when the gas flow measured was injected with liquid. This test was performed in a multiphase flow calibration facility. A vortex flowmeter of 50 mm in diameter was installed in a 100 mm test section. The gas volume flow rate was held in 141m3/h and the liquid was injected into the gas flow. The liquid volume fractions used at the gas volume flow rate were 0.0106%, 0.0213%,0.0355%,0.0496%,0.0638%,0.0780% and 0.0922%. The small amount of liquid in the gas as discrete droplet is called discrete liquid phase. Analysis on the vortex shedding frequency obtained from a frequency spectra showed that the strouhal values changed from 0.305 to 0.385 with the discrete liquid phase increasing and the total uncertainty of vortex flowmeter was from 0.869% to 2.196%. The experimental result can supply experimental basis for the measurement error correction of vortex flowmeter worked in gas flow with discrete liquid phase.
2
Li, Liang Chao. "CFD-DPM Modeling of Gas-Liquid Flow in a Stirred Vessel". Advanced Materials Research 550-553 (lipiec 2012): 979–83. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.979.
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Gas-liquid flow in a stirred vessel was simulated numerically with computational fluid dynamics(CFD). Gas was treated as discrete phase and described by discrete phase model (DPM), while the liquid was considered as a continuum and solved under Euler reference frame. The liquid velocity, gas holdup and gas residence time distribution in the stirred vessel were predicted. The simulation results show that gas dispersion in the stirred vessel is very non-uniformity and high gas holdup is found in the centre of the stirred vessel and vortexes while relatively low in bottom region and region between two impellers. Liquid velocity has great influence on bubble residence time and size distributions.
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Chaitanya, G. V. A., i G. S. Gupta. "Liquid flow in heap leaching using the discrete liquid flow model and graph-based void search algorithm". Hydrometallurgy 221 (sierpień 2023): 106151. http://dx.doi.org/10.1016/j.hydromet.2023.106151.
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Hagen, Thijmen, Stefan Luding, Devaraj van der Meer, Vanessa Magnanimo i Ahmed Jarray. "Liquid migration in flowing granular materials". EPJ Web of Conferences 249 (2021): 09001. http://dx.doi.org/10.1051/epjconf/202124909001.
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In partially wet granular beds, liquid migrates between particles due to collisions and contacts. This, in turn, influences the flow behaviour of the granular bed. We investigate liquid redistribution in moving monodisperse particles in a rotating drum using Discrete Element Method (DEM) simulations. For weak capillary forces, liquid re-distribution, induced by the continuous flow of particles, leads to concentration of the liquid in the core of the bed, where the flow is quasi-static. High capillary forces reduce the surface flow speed and granular temperature. This decreases liquid bridges rupturing in the flowing layer, allowing the liquid to remain in the outer region of the bed.
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Gadi, Venkat Arunchaitanya, i Govind Sharan Gupta. "Discrete Liquid Flow Behavior in a 2D Random Packed Bed". ISIJ International 63, nr 5 (15.05.2023): 810–21. http://dx.doi.org/10.2355/isijinternational.isijint-2022-529.
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Zhang, Junping, Norman Epstein, John R. Grace i Kokseng Lim. "Bubble Characteristics in a Developing Vertical Gas–Liquid Upflow Using a Conductivity Probe". Journal of Fluids Engineering 122, nr 1 (12.10.1999): 138–45. http://dx.doi.org/10.1115/1.483250.
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Experiments were carried out in an 82.6-mm-dia column with a perforated distributor plate. Conductivity probes on the axis of the column were used to measure local bubble properties in the developing flow region for superficial air velocities from 0.0018 to 6.8 m/s and superficial water velocities from 0 to 0.4 m/s, corresponding to the discrete bubble, dispersed bubble, coalesced bubble, slug, churn, bridging, and annular flow regimes. Bubble frequency increased linearly with gas velocity in the discrete and dispersed bubble regimes. Bubble frequency also increased with gas velocity in the slug flow regime, but decreased in the churn and bridging regimes. Bubble chord length and its distribution were smaller and narrower in the dispersed than in the discrete bubble regime. Both the average and standard deviation of the bubble chord length increased with gas velocity in the discrete, dispersed, and churn flow regimes. However, the average bubble chord length did not change significantly in the slug flow regime due to the high population of small bubbles in the liquid plugs separating Taylor bubbles. The bubble travel length, defined as the product of local gas holdup and local bubble velocity divided by local bubble/void frequency, is used to correlate bubble characteristics and to characterize the flow regimes. [S0098-2202(00)00101-2]
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Roques, J. F., V. Dupont i J. R. Thome. "Falling Film Transitions on Plain and Enhanced Tubes". Journal of Heat Transfer 124, nr 3 (10.05.2002): 491–99. http://dx.doi.org/10.1115/1.1458017.
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In falling film heat transfer on horizontal tube bundles, liquid flow from tube to tube occurs as a falling jet that can take on different flow modes. At low flow rates, the liquid film falls as discrete droplets. At higher flow rates, these droplets form discretely spaced liquid columns. At still higher flow rates, the film falls as a continuous sheet of liquid. Predicting the flow transitions between these flow modes is an essential step in determining the heat transfer coefficient for the particular flow mode, whether for a single phase process or for falling film condensation or evaporation. Previous studies have centered mostly on falling films on plain tube arrays. The objective of the present study is to extend the investigation to tubes with enhanced surfaces: a low finned tube, an enhanced boiling tube and an enhanced condensation tube. The effect of tube spacing on flow transition has also been investigated. The test fluids were water, glycol and a glycol-water mixture. The adiabatic experimental results show that the flow mode transition thresholds for the enhanced boiling tube are very similar to those of the plain tube while the fin structure of the other two enhanced tubes can significantly shift their transition thresholds.
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李, 静. "A Second-Order Fully Discrete Scheme for Nematic Liquid Crystal Flow". Advances in Applied Mathematics 11, nr 04 (2022): 1700–1707. http://dx.doi.org/10.12677/aam.2022.114185.
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Wang, Cheng Jun, Long Li, Chang Guo Xue i Qiong Liu. "Research on the Influence of Multidimensional Vibration on Casting Filling Capacity Based on Discrete Element Method". Key Engineering Materials 693 (maj 2016): 1263–71. http://dx.doi.org/10.4028/www.scientific.net/kem.693.1263.
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To analyze liquid metal flow in mold under multidimensional vibration condition, discrete element method (DEM) is taken to approximately stimulate liquid metal flow and to simulate numerically liquid metal flow filling process in casting technique under multidimensional vibration. The orthogonal experiment design is taken to study vibration dimension, frequency as well as amplitude influence on liquid metal filling capacity; Through EDEM platform, numerical simulation research in each test scheme can be carried out to get influence of filling time upon sensitivity degree of each parameter index so as to select the optimal test scheme. Casting experiment results in the self-made solidification test-bed under multidimensional vibration match the numerical simulation, showing that multidimensional vibration could significantly improve filling capacity of castings.
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FAN, XIAOFENG, i JIANGFENG WANG. "A MARKER-BASED EULERIAN-LAGRANGIAN METHOD FOR MULTIPHASE FLOW WITH SUPERSONIC COMBUSTION APPLICATIONS". International Journal of Modern Physics: Conference Series 42 (styczeń 2016): 1660159. http://dx.doi.org/10.1142/s2010194516601599.
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The atomization of liquid fuel is a kind of intricate dynamic process from continuous phase to discrete phase. Procedures of fuel spray in supersonic flow are modeled with an Eulerian-Lagrangian computational fluid dynamics methodology. The method combines two distinct techniques and develops an integrated numerical simulation method to simulate the atomization processes. The traditional finite volume method based on stationary (Eulerian) Cartesian grid is used to resolve the flow field, and multi-component Navier-Stokes equations are adopted in present work, with accounting for the mass exchange and heat transfer occupied by vaporization process. The marker-based moving (Lagrangian) grid is utilized to depict the behavior of atomized liquid sprays injected into a gaseous environment, and discrete droplet model 13 is adopted. To verify the current approach, the proposed method is applied to simulate processes of liquid atomization in supersonic cross flow. Three classic breakup models, TAB model, wave model and K-H/R-T hybrid model, are discussed. The numerical results are compared with multiple perspectives quantitatively, including spray penetration height and droplet size distribution. In addition, the complex flow field structures induced by the presence of liquid spray are illustrated and discussed. It is validated that the maker-based Eulerian-Lagrangian method is effective and reliable.
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Wang, G. X., D. Y. Liu, J. D. Litster, A. B. Yu, S. J. Chew i P. Zulli. "Experimental and numerical simulation of discrete liquid flow in a packed bed". Chemical Engineering Science 52, nr 21-22 (listopad 1997): 4013–19. http://dx.doi.org/10.1016/s0009-2509(97)00244-3.
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Bezrukov, Artem, i Yury Galyametdinov. "Orientation Behavior of Nematic Liquid Crystals at Flow-Wall Interfaces in Microfluidic Channels". Coatings 13, nr 1 (12.01.2023): 169. http://dx.doi.org/10.3390/coatings13010169.
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This work characterizes the orientation behavior of nematic liquid crystals in pressure-driven flows of microfluidic channels at interfaces between the flow and microchannel walls. The impact of flow velocity and microchannel geometry on the orientation of liquid crystals in single-phase and two-phase flows is discussed. Polarizing optical microscopy images revealed the homeotropic orientation of liquid crystal molecules at microchannel walls at zero flow velocities, which gradually transitioned into planar alignment along the microchannel axis when the flow velocity increased in the 50 μm/s to 5 mm/s range. Liquid crystal droplets demonstrated homeotropic or planar alignment depending on the sizes of droplets and flow velocities. The polarized light pattern from homeotropically aligned droplets deposited on microchannel walls was found to be logarithmically proportional to the flow velocity in the 2 to 40 mm/s range. The revealed behavior of nematic liquid crystals at microchannel wall surfaces in dynamic flow conditions offers new tools for on-demand control of the optical properties of microfluidic devices and can contribute to the development of analytical lab-on-chip tools with internal continuous or discrete liquid crystal layers for flow characterization in microchannel confinement.
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Sun, Chunhua, Zhi Ning, Xinqi Qiao, Ming Lv, Juan Fu, Jin Zhao i Xintao Wang. "Numerical simulation of gas–liquid flow behavior in the nozzle exit region of an effervescent atomizer". International Journal of Spray and Combustion Dynamics 11 (styczeń 2019): 175682771882159. http://dx.doi.org/10.1177/1756827718821592.
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The pressure drop and particular geometric structure of the nozzle exit region of an effervescent atomizer cause complex changes in the flow pattern, which could affect the spray performance. In this study, the gas–liquid two-phase flow behavior in the nozzle exit region of the effervescent atomizer was investigated numerically. The results show that the flow behaviors in the nozzle exit region have disparate characteristics with different upstream flow regimes. For upstream churn flow, the liquid film morphology is closely related to fluctuation in the gas–liquid velocity, and the flow parameters (fluids’ velocities and gas void fraction) at the exit section vary regularly with time. For upstream bubbly flow, the instantaneous gas void fraction is determined by the bubble distribution inside the mixing chamber. The bubble will form a tadpole-like shape as a result of the complex flow field and the surface tension. The flow parameters at the exit section are in an oscillatory decay, and the fluctuation amplitude is larger than for churn flow. For upstream slug flow, the gas void fraction varies significantly with time. The discrete characteristic of the gas–liquid flow parameters at exit section is very obvious.
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Lezzi, A. M., i A. Prosperetti. "The stability of an air film in a liquid flow". Journal of Fluid Mechanics 226 (maj 1991): 319–47. http://dx.doi.org/10.1017/s0022112091002409.
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A number of processes in which air is entrained in a flow appear to involve the formation of a thin air film between a relatively fast liquid stream and a region of slow recirculation. Eventually, the film breaks into bubbles. This study addresses a possible mechanism causing this process. The linear stability of a vertical film of a viscous gas bounded by liquid in uniform motion on one side, and by liquid at rest on the other side, is studied. Instabilities are found that, depending on the parameter values of the undisturbed flow, are controlled by two basic mechanisms. One is due to the velocity jump across the film and can be related to the usual Kelvin–Helmholtz instability. The second one is controlled by the viscosity jump across the air liquid interfaces. The relation between the remainder of the discrete spectrum and the spectrum of other parallel shear flows bounded by solid or free surfaces is also discussed.
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Wang, Peng, Xinyu Zhu i Yi Li. "Analysis of Flow and Wear Characteristics of Solid–Liquid Two-Phase Flow in Rotating Flow Channel". Processes 8, nr 11 (21.11.2020): 1512. http://dx.doi.org/10.3390/pr8111512.
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To study the flow characteristics and the wear distribution of pumps at different rotation speeds, a rotating disc with three blades was designed for experiments. Numerical simulations were conducted using a computational fluid dynamics-discrete phase model (CFD–DPM) approach. The experimental and numerical results were compared, and the flow characteristics and wear behaviors were determined. As the speed increased, the particles at the blade working surface aggregated. The particle velocity gradually increased at the outlet of the channel. The severe wear areas were all located in the outlet area of the blade working surface, and the wear area extended toward the inlet area of the blade with increasing speed. The wear rate of the blade surface increased as the speed increased, and an area with a steady wear rate appeared at the outlet area of the blade. When the concentration was more than 8%, the severe wear areas were unchanged at the same speed. When the speed increased, the severe wear areas of the blade produced wear ripples, and the area of the ripples increased with increasing speed. The height difference between the ripples along the flow direction on the blade became larger as the speed increased.
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Koropchak, John A., Lori Allen i Joe M. Davis. "Aerosol Interfacing Effects on Discrete Sample Introduction Coupled with Spectrometric Detection". Applied Spectroscopy 46, nr 4 (kwiecień 1992): 682–89. http://dx.doi.org/10.1366/0003702924125023.
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Aerosol techniques are commonly employed to interface discrete sampling techniques (flow injection analysis and liquid chromatography) with various detectors. The effects of these interfaces on discrete signals have not been described, nor has a rationale been established for presumed differences in band broadening due to aerosol-phase extra-column volume, compared to liquid-phase extra-column volume. In this report, the effects of laminar flow through several transport geometries on signal recovery and band broadening for both wet and desolvated aerosols are investigated. Data presented for the conditions studied indicate that signal losses with linear systems are primarily affected by gravitational settling. Increases in residence time lead to larger losses. Centrifugal effects, which lead to higher losses with coiled systems at high linear velocities, however, appear to have a stabilizing effect at lower velocities. Desolvation significantly reduces the level of gravitational or centrifugal losses via reduction in particle sizes. Band broadening results primarily from convection within laminar flow systems. This result was established on the basis of comparison of real signals with those generated from a convolution routine which mimics the effects of convective dispersion within laminar flows. The relatively high flow rates of aerosol transport systems result in short residence times and small effects of large transport volumes on dispersion. Sample losses also appear to offset band broadening to some extent by reducing peak tailing. Conditions providing efficient analyte transport and signal recovery, as well as low dispersion, can be established.
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Li, Jia-Xin, Yun-Ze Li, En-Hui Li i Tong Li. "Numerical Investigation on the Thermodynamic Characteristics of a Liquid Film upon Spray Cooling Using an Air-Blast Atomization Nozzle". Entropy 22, nr 3 (9.03.2020): 308. http://dx.doi.org/10.3390/e22030308.
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This paper developed a three-dimensional model to simulate the process of atomization and liquid film formation during the air-blast spray cooling technological process. The model was solved using the discrete phase model method. Several factors including the thermodynamic characteristics of the liquid film as well as the spray quality with different spray mass flow rates under different spray heights were numerically investigated and discussed. The results show that the varied spray height has little effect on the Sauter Mean Diameter (d32) of the spray droplet, while the thermodynamic characteristics of liquid film including the liquid film height, the liquid film velocity, and the liquid film generation rate are sensitive to the change of the spray height. With the growth of spray mass flow rates, d32, the liquid film generation rate and liquid film height become larger, while the liquid film velocity with different spray mass flow rates has a similar velocity distribution, indicating that the spray mass flow rate has little effect on the liquid film velocity. The average d32 of droplet size shows a sharp drop when sprayed from the nozzle in a short period of time (<1.5 ms), then approaching smoothness, below a value of 40 μ m , the spray status tends to be stable.
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Li, Bo, Jian ming Wang, Qi Wang, Xiu yan Li i Xiaojie Duan. "A novel gas/liquid two-phase flow imaging method through electrical resistance tomography with DDELM-AE sparse dictionary". Sensor Review 40, nr 4 (11.04.2020): 407–20. http://dx.doi.org/10.1108/sr-01-2019-0018.
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Purpose The purpose of this paper is to explore gas/liquid two-phase flow is widely existed in industrial fields, especially in chemical engineering. Electrical resistance tomography (ERT) is considered to be one of the most promising techniques to monitor the transient flow process because of its advantages such as fast respond speed and cross-section imaging. However, maintaining high resolution in space together with low cost is still challenging for two-phase flow imaging because of the ill-conditioning of ERT inverse problem. Design/methodology/approach In this paper, a sparse reconstruction (SR) method based on the learned dictionary has been proposed for ERT, to accurately monitor the transient flow process of gas/liquid two-phase flow in a pipeline. The high-level representation of the conductivity distributions for typical flow regimes can be extracted based on denoising the deep extreme learning machine (DDELM) model, which is used as prior information for dictionary learning. Findings The results from simulation and dynamic experiments indicate that the proposed algorithm efficiently improves the quality of reconstructed images as compared to some typical algorithms such as Landweber and SR-discrete fourier transformation/discrete cosine transformation. Furthermore, the SR-DDELM has also used to estimate the important parameters of the chemical process, a case in point is the volume flow rate. Therefore, the SR-DDELM is considered an ideal candidate for online monitor the gas/liquid two-phase flow. Originality/value This paper fulfills a novel approach to effectively monitor the gas/liquid two-phase flow in pipelines. One deep learning model and one adaptive dictionary are trained via the same prior conductivity, respectively. The model is used to extract high-level representation. The dictionary is used to represent the features of the flow process. SR and extraction of high-level representation are performed iteratively. The new method can obviously improve the monitoring accuracy and save calculation time.
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Wang, Yanping, Ruilin Tao, Chuanfeng Han, Weiqin Li, Tielin He i Zuchao Zhu. "Numerical study on flow and wear characteristics of dense fine particle solid–liquid two-phase flow in centrifugal pump". AIP Advances 12, nr 4 (1.04.2022): 045109. http://dx.doi.org/10.1063/5.0079425.
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The solid–liquid two-phase centrifugal pump is one of the core power equipment of solid phase material hydraulic transportation, widely used in hydraulic engineering, petrochemical industry, marine metal mineral exploitation, urban sewage treatment, and other sectors of the national economy. There is a significant increase in the need to transport dense fine particle slurry in industrial production. Under this condition, the influence of particle parameters on the performance of the centrifugal pump is still not clear. In order to study the flow and wear characteristics of dense fine particle solid–liquid two-phase transported by an open impeller centrifugal pump, the Re-Normalization Group k − ε and dense discrete phase models in Fluent were used to describe the characteristics of the solid–liquid two-phase flow. The numerical model is validated with the experimental data of the pump’s performance. The study indicates that the particle size and concentration have great influence on the wear of the impeller. The wear of the blade pressure surface is the most serious. With the increase of particle concentration and size, the wear area expands to the leading edge and the upper surface of the blade. These results can provide supporting theories for the design of a dense fine particle solid–liquid two-phase medium conveying pump.
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Gersey, C. O., i I. Mudawar. "Orientation Effects on Critical Heat Flux From Discrete, In-Line Heat Sources in a Flow Channel". Journal of Heat Transfer 115, nr 4 (1.11.1993): 973–85. http://dx.doi.org/10.1115/1.2911394.
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The effects of flow orientation on critical heat flux (CHF) were investigated on a series of nine in-line simulated microelectronic chips in Fluorinert FC-72. The chips were subjected to coolant in upflow, downflow, or horizontal flow with the chips on the top or bottom walls of the channel with respect to gravity. Changes in angle of orientation affected CHF for velocities below 200 cm/s, with some chips reaching CHF at heat fluxes below the pool boiling and flooding-induced CHF values. Increased subcooling was found to dampen this adverse effect of orientation slightly. Critical heat flux was overwhelmingly caused by localized dryout of the chip surface. However, during the low velocity downflow tests, low CHF values were measured because of liquid blockage by vapor counterflow and vapor stagnation in the channel. At the horizontal orientation with downward-facing chips, vapor/liquid stratification also yielded low CHF values. Previously derived correlations for water and long, continuous heaters had limited success in predicting CHF for the present discontinuous heater configuration. Because orientation has a profound effect on the hydrodynamics of two-phase flow and, consequently, on CHF for small inlet velocities, downflow angles should be avoided, or when other constraints force the usage of downflow angles, the inlet liquid velocity should be sufficiently large.
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Su, Te Cheng, Catherine O'Sullivan, Hideyuki Yasuda i Christopher M. Gourlay. "Understanding the Rheological Transitions in Semi-Solid Alloys by a Combined <i>In Situ</i> Imaging and Granular Micromechanics Modeling Approach". Solid State Phenomena 327 (10.01.2022): 127–32. http://dx.doi.org/10.4028/www.scientific.net/ssp.327.127.
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To gain better understanding of rheological transitions from suspension flow to granular deformation and shear cracking, this research conducted shear-deformation on globular semi-solid Al-Cu alloys to study the rheological behavior of semi-solid as a function of solid fraction (38% - 85%) and shear rate (10-4 – 10-1 s-1) under real-time synchrotron radiography observation. By analyzing 17 X-ray imaging datasets, we define three rheological transitions: (i) the critical solid fraction from a suspension to a loosely percolating assembly; (ii) from the net contraction of a loose assembly to the net dilation of a densely packed assembly, and (iii) to shear cracking at high solid fraction and shear rate. Inspired by in-situ observations of semi-solid deformation showing a disordered assembly of percolating crystals in partially-cohesive contact with liquid flow, we reproduced a two-phase sample using the coupled lattice Boltzmann method-discrete element method (LBM-DEM) simulation approach for granular micromechanical modeling. In DEM, each globular Al grain is represented by a discrete element, and the flow of interstitial liquid is solved by LBM. The LBM-DEM simulations show quantitative agreement of semi-solid strain localization with the experiments and are used to explore the components involved in the shear rate dependence of the transitions, and the role of liquid pressure on the initiation of shear cracking.
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Hu, X., i A. M. Jacobi. "The Intertube Falling Film: Part 2—Mode Effects on Sensible Heat Transfer to a Falling Liquid Film". Journal of Heat Transfer 118, nr 3 (1.08.1996): 626–33. http://dx.doi.org/10.1115/1.2822678.
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When a liquid film falls from one horizontal tube to another below it, the flow may take the form of discrete droplets, jets, or a continuous sheet; the mode plays an important role in the heat transfer. Experiments are reported that explore the local heat transfer behavior for each of these flow patterns, and the results are related to the important features of the flow. Spatially averaged Nusselt numbers are presented and discussed, and new mode-specific design correlations are provided. This research is part of an overall study of horizontal-tube, falling-film flow and heat transfer.
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Delnoij, E., F. A. Lammers, J. A. M. Kuipers i W. P. M. van Swaaij. "Dynamic simulation of dispersed gas-liquid two-phase flow using a discrete bubble model". Chemical Engineering Science 52, nr 9 (maj 1997): 1429–58. http://dx.doi.org/10.1016/s0009-2509(96)00515-5.
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Kmec, Jakub, Miloslav Šír, Tomáš Fürst i Rostislav Vodák. "Semi-continuum modeling of unsaturated porous media flow to explain Bauters' paradox". Hydrology and Earth System Sciences 27, nr 6 (24.03.2023): 1279–300. http://dx.doi.org/10.5194/hess-27-1279-2023.
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Abstract. In the gravity-driven free infiltration of a wetting liquid into a homogeneous unsaturated porous medium, the flow pattern is known to depend significantly on the initial saturation. Point source infiltration of a liquid into an initially dry porous medium produces a single finger with an oversaturated tip and an undersaturated tail. In an initially wet medium, a diffusion-like plume is produced with a monotonic saturation profile. We present a semi-continuum model, based on a proper scaling of the retention curve, which is discrete in space and continuous in time. We show that the semi-continuum model is able to describe this transition and to capture the experimentally observed dependence of the saturation overshoot and the finger velocity on the initial saturation.
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Mudawar, Issam, i Douglas E. Maddox. "Enhancement of Critical Heat Flux From High Power Microelectronic Heat Sources in a Flow Channel". Journal of Electronic Packaging 112, nr 3 (1.09.1990): 241–48. http://dx.doi.org/10.1115/1.2904373.
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Several surface augmentation techniques were examined in an investigation of enhancement of critical heat flux (CHF) from a simulated electronic chip to a fluorocarbon (FC-72) liquid in a vertical channel. A parametric comparison of boiling performances is presented for a smooth surface and for surfaces with low-profile microgrooves, low-profile microstuds, and high-profile pin fins. Critical heat fluxes as high as 361 W/cm2 were achieved using a combination of moderate flow velocity, high subcooling and surface enhancement. A semiempirical model constructed previously for CHF from a smooth discrete heat source to saturated or subcooled liquid flow, was found successful in correlating CHF data for the three enhanced surfaces.
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Cwudziński, A. "Numerical Simulation of Behaviour a Non-Metallic Inclusions in an One-Strand Slab Tundish with Steel Flow Controll Devices". Archives of Metallurgy and Materials 56, nr 3 (1.09.2011): 611–18. http://dx.doi.org/10.2478/v10172-011-0066-0.
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Numerical Simulation of Behaviour a Non-Metallic Inclusions in an One-Strand Slab Tundish with Steel Flow Controll DevicesAn effective refining of liquid steel can be carried out either in a tundish or in the mould of a CSC machine. Being a flow reactor, the tundish performs the function of a link between the steelmaking ladle and the mould. Owing to this fact, the liquid steel resides in the tundish for a specific time, which enables the tundish to be used for refining purposes. For modification oftundish internal working space, two types of flow control device (FCD), namely a ceramic gas-permeable barrier and a subflux turbulence controller (STC), were proposed. For simulation of movement of gas phase and non-metallic inclusions, a discrete phase model was used. The obtained results unambiguously indicate which of the proposed tundish equipment configurations will be more advantageous for intensifying the process of liquid steel refining from NMIs.
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Chen, Fuzhen, Haorui Li, Yang Gao i Hong Yan. "Two-particle method for liquid–solid two-phase mixed flow". Physics of Fluids 35, nr 3 (marzec 2023): 033317. http://dx.doi.org/10.1063/5.0140599.
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Liquid–solid two-phase flows are a very important class of multiphase flow problems widely existing in industry and nature. This paper establishes a two-phase model for liquid–solid two-phase flows considering multiphase states of granular media. The volume fraction is defined by the solid phase, determining the material properties of the two phases, and momentum is exchanged between the phases by drag and pressure gradient forces. On this basis, a two-particle method for simulating the liquid–solid two-phase flow is proposed by coupling smoothed particle hydrodynamics with smoothed discrete particle hydrodynamics. The coupling framework for the two-particle method is constructed, and the coupling between the algorithms is realized through interphase momentum exchange, volume fraction constraint, and field variable sharing. The liquid phase density changes are divided into two types. One is caused by weak compressibility, and the other is caused by changes in the solid phase volume fraction. The former is used to calculate the liquid-phase flow field, and the latter is used to calculate the two-phase coupling to solve the problem of sudden bulk density changes in the liquid phase caused by changes in particle volume fractions. The two-particle method maintains the dual advantages of the particle method for free interface tracking and material point tracking for particles. The new method is validated using a series of fundamental test cases, and comparison with experimental results shows that the new method is suitable for resolving liquid–solid two-phase flow problems and has significant practical value for future simulations of mudflow motions, coastal breakwaters, and landslide surges.
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Wang, Y. Q., Ming Rang Cao, Sheng Qiang Yang i Wen Hui Li. "Numerical Simulation of Liquid-Solid Two-Phase Flow Field in Discharge Gap of High-Speed Small Hole EDM Drilling". Advanced Materials Research 53-54 (lipiec 2008): 409–14. http://dx.doi.org/10.4028/www.scientific.net/amr.53-54.409.
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The flow field characteristics have a significant effect on the machining stability in high-speed small hole EDM drilling. Thus, Lagrangian discrete phase model (DPM) has been developed to simulate the gap liquid-solid two-phase flow field. The numerical calculation is based on the standard k-ε turbulent model, and the SIMPLEC algorithm is used in the simulation. All the governing equations are solved by software Fluent 6.2. Through numerical simulation, the pressure distribution, the velocity distribution of the dielectric liquid, traces of debris particles, and the debris particle concentration were obtained. The flow field characteristics under different pressures and drilling depths were obtained through simulations. Finally, experiments were carried out to investigate the effects of the flush velocity at exit obtained through simulation on material removal rate (MRR).
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Zhao, Yongpeng, Xiangyang Sun i Zaiping Nie. "Streaming Potential in Gas Phase Discrete Unsaturated Pore". Electronics 12, nr 1 (25.12.2022): 72. http://dx.doi.org/10.3390/electronics12010072.
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The seismoelectric effect of porous media is the main basis for seismoelectric logging. At present, most of the studies on the seismoelectric effect in unsaturated porous media adopt the model of pores with continuous distribution of gas and liquid. There is a lack of theoretical research on the micro mechanism of the seismoelectric effect of unsaturated porous media with discrete gas phase, and the existing studies do not consider the effect of the electric double layer at the gas–liquid interface on the seismoelectric effect. Based on the capillary model, this work adopted the gas phase discrete model, combined the electric double layer theory and the seepage principle, considered the effect of electric double layer at the pore wall and the gas–liquid interface, and studied the micro principle of the seismoelectric effect of unsaturated porous media. Firstly, we studied the variation of gas–water two-phase flow pattern with saturation in unsaturated pores, then proposed the equivalent principle of series circuits, deduced the effective streaming current and conductance of a pore containing multiple bubbles, and then deduced the streaming potential coupling coefficient in the unsaturated pores. We also studied the effect of pore parameters such as saturation, pore size, bubble spacing, pore fluid viscosity, and salinity on the streaming potential coupling coefficient. The results show that the streaming potential coupling coefficient first increases and then decreases with the decrease in saturation, which is the same as the trend measured in Allègre’s experiment, and provide a theoretical explanation for the non-monotonic change in the coupling coefficient with saturation in unsaturated porous media.
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Ren, Junjie, Ping Guo i Zhaoli Guo. "Rectangular Lattice Boltzmann Equation for Gaseous Microscale Flow". Advances in Applied Mathematics and Mechanics 8, nr 2 (kwiecień 2014): 306–30. http://dx.doi.org/10.4208/aamm.2014.m672.
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AbstractThe lattice Boltzmann equation (LBE) is considered as a promising approach for simulating flows of liquid and gas. Most of LBE studies have been devoted to regular square LBE and few works have focused on the rectangular LBE in the simulation of gaseous microscale flows. In fact, the rectangular LBE, as an alternative and efficient method, has some advantages over the square LBE in simulating flows with certain computational domains of large aspect ratio (e.g., long micro channels). Therefore, in this paper we expand the application scopes of the rectangular LBE to gaseous microscale flow. The kinetic boundary conditions for the rectangular LBE with a multiple-relaxation-time (MRT) collision operator, i.e., the combined bounce-back/specular-reflection (CBBSR) boundary condition and the discrete Maxwell's diffuse-reflection (DMDR) boundary condition, are studied in detail. We observe some discrete effects in both the CBBSR and DMDR boundary conditions for the rectangular LBE and present a reasonable approach to overcome these discrete effects in the two boundary conditions. It is found that the DMDR boundary condition for the square MRT-LBE can not realize the real fully diffusive boundary condition, while the DMDR boundary condition for the rectangular MRT-LBE with the grid aspect ratio a≠1 can do it well. Some numerical tests are implemented to validate the presented theoretical analysis. In addition, the computational efficiency and relative difference between the rectangular LBE and the square LBE are analyzed in detail. The rectangular LBE is found to be an efficient method for simulating the gaseous microscale flows in domains with large aspect ratios.
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Yuan, Zhe, Wen Xing Ma, Wei Cai, Li Dan Fan i Jian Jun Song. "Temperature Field Analysis on the Hydrodynamic Retarder of Heavy Vehicle". Advanced Materials Research 503-504 (kwiecień 2012): 1025–28. http://dx.doi.org/10.4028/www.scientific.net/amr.503-504.1025.
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According to the working characteristics of the hydrodynamic retarder, the hydrodynamic retarder D300 is chosen in this research. Based on three-dimensional flow theory, the internal temperature fields of hydrodynamic retarder with different liquid-filled ratios of 100%, 75%, 50%, 25% are numerically simulated. The standard k-ε model is chosen as turbulent model for calculation. The SIMPLEC algorithm is chosen as velocity-pressure coupling algorithm and the second order upwind scheme is used as discrete method. The mixture multiphase model is used to calculate the unsteady gas-liquid two-phase flow in the condition of partial charging. Through simulating and analyzing, it provides an important theoretical basis for the heat exchange of the hydrodynamic retarder at different gears.
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Aghaee, Mohammad, Rouhollah Ganjiazad, Ramin Roshandel i Mohammad Ali Ashjari. "Two-phase flow separation in axial free vortex flow". Journal of Computational Multiphase Flows 9, nr 3 (24.07.2017): 105–13. http://dx.doi.org/10.1177/1757482x17699411.
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Multi-phase flows, particularly two-phase flows, are widely used in the industries, hence in order to predict flow regime, pressure drop, heat transfer, and phase change, two-phase flows should be studied more precisely. In the petroleum industry, separation of phases such as water from petroleum is done using rotational flow and vortices; thus, the evolution of the vortex in two-phase flow should be considered. One method of separation requires the flow to enter a long tube in a free vortex. Investigating this requires sufficient knowledge of free vortex flow in a tube. The present study examined the evolution of tube-constrained two-phase free vortex using computational fluid dynamics. The discretized equations were solved using the SIMPLE method. It was determined that as the liquid flows down the length of the pipe, the free vortex evolves into combined forced and free vortices. The tangential velocity of the free and forced vortices also decreases in response to viscosity. It is shown that the concentration of the second discrete phase (oil) is greatest at the center of the pipe in the core of the vortex. This concentration is at a maximum at the outlet of the pipe.
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GASSIAT, PAUL, HUYÊN PHAM i MIHAI SÎRBU. "OPTIMAL INVESTMENT ON FINITE HORIZON WITH RANDOM DISCRETE ORDER FLOW IN ILLIQUID MARKETS". International Journal of Theoretical and Applied Finance 14, nr 01 (luty 2011): 17–40. http://dx.doi.org/10.1142/s0219024911006243.
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We study the problem of optimal portfolio selection in an illiquid market with discrete order flow. In this market, bids and offers are not available at any time but trading occurs more frequently near a terminal horizon. The investor can observe and trade the risky asset only at exogenous random times corresponding to the order flow given by an inhomogenous Poisson process. By using a direct dynamic programming approach, we first derive and solve the fixed point dynamic programming equation satisfied by the value function, and then perform a verification argument which provides the existence and characterization of optimal trading strategies. We prove the convergence of the optimal performance, when the deterministic intensity of the order flow approaches infinity at any time, to the optimal expected utility for an investor trading continuously in a perfectly liquid market model with no-short sale constraints.
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Hanus, Robert, Marcin Zych, Barbara Wilk, Marek Jaszczur i Dariusz Świsulski. "Signals features extraction in radioisotope liquid-gas flow measurements using wavelet analysis". EPJ Web of Conferences 213 (2019): 02023. http://dx.doi.org/10.1051/epjconf/201921302023.
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Knowledge of the structure of a flow is significant for the proper conduct of a number of industrial processes. In this case, a description of a two-phase flow regimes is possible by use of the time-series analysis in time, frequency and state-space domain. In this article the Discrete Wavelet Transform (DWT) is applied for analysis of signals obtained for water-air flow using gamma ray absorption. The presented method was illustrated by use data collected in experiments carried out on the laboratory hydraulic installation with a horizontal pipe, equipped with two Am-241 radioactive sources and scintillation probes with NaI(Tl) crystals. Signals obtained from detectors for slug, plug, bubble, and transitional plug – bubble flows were considered in this work. The recorded raw signals were analyzed and wavelet energy was extracted using multiresolution analysis. It was found that energies of wavelet approximation at 1-5 levels are useful to recognize the structure of the flow.
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Luca, Luigi De, i Carosena Meola. "Surfactant effects on the dynamics of a thin liquid sheet". Journal of Fluid Mechanics 300 (10.10.1995): 71–85. http://dx.doi.org/10.1017/s0022112095003612.
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The dynamics of a free-surface slender two-dimensional stream (liquid sheet) issuing from a nozzle in the gravitational field in still air, under the effect of surface-active agents, are analysed experimentally. The particular test section geometry (the liquid is forced to assume a bidimensional form between two vertical guides and a horizontal plate placed at a certain variable distance from the nozzle exit section) employed in this study gives rise to various flow regimes depending on the governing parameters: liquid flow rate, sheet height, surface pressure, gravity. Two basic phenomena are observed: thinning of the sheet (with recirculating motion inside it) and sheet-threadlines transition. For a certain surfactant (bulk) concentration, there exists a minimum critical flow rate value for which the sheet is seen to thin starting at both of the sheet bottom corners. A ridge, usually referred to as a Reynolds ridge in the literature, separates the sheet from the thin-film regions. The thin films exhibit recirculating flows (caused by the onset of surfactant-induced surface-pressure-driven convection in the gravitational field) and extend to the entire rectangular interface as the flow rate is reduced. At zero flow rate the thinned sheet resembles a plane vertical soap film showing a recirculating cellular structure. These phenomena are linked to the presence of surface-active material adsorbed at the liquid-air interface and occur when the sheet height exceeds a critical value. Otherwise, at a critical flow rate value the liquid sheet breaks up into an array of (more or less regularly distributed) discrete threadlines (vertical jets), whose spacing depends on the surface tension of the test liquid.
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Li, Yi, Xiaodong Zeng, Wenshuai Lv i Zhaohui He. "Centrifugal pump wear for solid–liquid two-phase flows based on computational fluid dynamics–discrete element method coupling". Advances in Mechanical Engineering 12, nr 7 (lipiec 2020): 168781402093795. http://dx.doi.org/10.1177/1687814020937951.
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In the conveying process of a solid–liquid two-phase medium, the wear of the flow passage components is unavoidable. In this study, the solid–liquid two-phase flow in a centrifugal pump was numerically simulated by computational fluid dynamics–discrete element method coupling. For particle diameters up to 3 mm, the particle–particle and particle–wall interactions were considered in the simulation. Two-phase performance and wear experiments for different flow rates and particle concentrations were conducted. The wear experiment was carried out for 48 h at each mass concentration. In these experiments, a paint film method was used to display the wear position, and the wall thickness of the flow passage was measured using an ultrasonic thickness gauge. The results show that the instantaneous wear rate of the impeller, volute, and wear plate in the pump changed periodically with the impeller rotation. The volute wall wear was related to the particle movement. With the increase in the particle mass concentration, the wear rate increased. However, the rate of increase of the wear rate decreased because the particles moved to the wall in the volute to form a particle layer. Increasing the concentration did not linearly increase the effect of the particles on the wall.
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Lyu, Xiuxiu, Yujie Zhu, Chi Zhang, Xiangyu Hu i Nikolaus A. Adams. "Modeling of Cavitation Bubble Cloud with Discrete Lagrangian Tracking". Water 13, nr 19 (28.09.2021): 2684. http://dx.doi.org/10.3390/w13192684.
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In this paper, a Lagrangian-Eulerian (LE) two-way coupling model is developed to numerically study the cavitation bubble cloud. In this model, the gas-liquid mixture is treated directly as a continuous and compressible fluid and the governing equations are solved by methods in Eulerian descriptions. An isobaric closure exhibiting better consistency properties is applied to evaluate the pressure of gas-liquid mixture. The dispersed gas/vapor bubbles are tracked in a Lagrangian fashion, and their compression and expansion are described by a modified Rayleigh-Plesset equation, which considers the close-by flow properties other than these of the infinity for each bubble. The performance of the present method is validated by a number of benchmark tests. Then, this model is applied to study how the bubble cloud affects the shape and propagation of a pressure wave when the pressure pulse travels through. In the end, a three-dimensional simulation of a vapor cloud’s Rayleigh collapse is carried out, and the induced extreme pressure is discussed in detail. The total bubble number’s influence on the extreme collapse pressure and the size distribution of bubbles during the collapse are also analyzed.
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Wang, Cheng-shan, Xiao-jing Mu, Shao-bo Zheng, Guo-chang Jiang, Xing-guo Xiao i Wen-zhong Wang. "A New Mathematical Model for Description of the Liquid Discrete Flow Within a Packed Bed". Journal of Iron and Steel Research International 15, nr 6 (czerwiec 2008): 16–23. http://dx.doi.org/10.1016/s1006-706x(08)60259-9.
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Salvador, Fernanda Falqueto, Nathcha Kare Gonçalves Silva, Marcos Antonio de Souza Barrozo i Luiz Gustavo Martins Vieira. "Study of the Capacity in a Totally Permeable Hydrocyclone". Materials Science Forum 802 (grudzień 2014): 250–55. http://dx.doi.org/10.4028/www.scientific.net/msf.802.250.
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Hydrocyclones are equipments that separate a discrete phase (solid, liquid or gas) from a continuous phase (liquid) by generating a centrifugal field. The objective of this work was to study, experimentally, the incorporation effect of cylindrical and conical permeable walls (CyCoFH) on an optimized geometry hydrocyclone (H11) to evaluate the equipment’s processing capacity. By inserting a filtering cone and cylinder, during the operation of these separators, besides the traditionally observed streams (underflow and overflow), there is an additional liquid stream resulting from the filtering process in the conical and cylindrical regions. Despite the low filtrate flow observed during this new equipment’s operation, it was found that the filtration is benefic to hydrocycloning. According to the main results, the CyCoFH hydrocyclone of lower permeability presented a greater processing capacity. The feed flow rate was 23% higher than the corresponding conventional hydrocyclone, in the same geometrical and operational conditions.
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Jeswani, A. L., i J. A. Roux. "Manufacturing Modeling of Three-Dimensional Resin Injection Pultrusion Process Control Parameters for Polyester/Glass Rovings Composites". Journal of Manufacturing Science and Engineering 129, nr 1 (15.08.2006): 143–56. http://dx.doi.org/10.1115/1.2383148.
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Pultrusion, sometimes referred to as continuous resin transfer molding process, is a continuous, cost-effective method for manufacturing composite materials with constant cross sections (such as rod stock, beams, channels, and tubing). The objective of this study is to improve the fiber reinforcement wetout and thus the quality of the pultruded part in the injection pultrusion process. The complete wetout of the dry reinforcement by the liquid resin depends on various design and process parameters. The process parameters modeled in this study are fiber pull speed, fiber volume fraction, and viscosity of the resin. In the present work, a three-dimensional finite volume technique is employed to simulate the liquid resin flow through the fiber reinforcement in the injection pultrusion process. The numerical model simulates the flow of polyester resin through the glass rovings and predicts the impact of the process parameters on wetout, resin pressure field, and resin velocity field. The location of the liquid resin flow front has been predicted for an injection slot as well as for five discrete injection ports.
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Klaučo, Martin, Ľuboš Čirka i Juraj Kukla. "Non-linear model predictive control of conically shaped liquid storage tanks". Acta Chimica Slovaca 11, nr 2 (1.10.2018): 141–46. http://dx.doi.org/10.2478/acs-2018-0020.
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Abstract This paper deals with the analysis and design of a model predictive control (MPC) strategy used in connection with level control in conically shaped industrial liquid storage tanks. The MPC is based on a non-linear dynamic model describing changes of the liquid level concerning changes in the inlet flow of the liquid. Euler discretization of the dynamic system was applied to transform con-tinuous time dynamics to its discrete-time counterpart used in non-linear MPC (NMPC) design. By means of a simulation case study, NMPC has been shown to track the changes of the liquid level, hence provides increased control performance. This paper also compares the traditional approach of optimal control, linear MPC, with the NMPC strategy.
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Fu, S. C., R. M. C. So i W. W. F. Leung. "A Discrete Flux Scheme for Aerodynamic and Hydrodynamic Flows". Communications in Computational Physics 9, nr 5 (maj 2011): 1257–83. http://dx.doi.org/10.4208/cicp.311009.241110s.
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AbstractThe objective of this paper is to seek an alternative to the numerical simulation of the Navier-Stokes equations by a method similar to solving the BGK-type modeled lattice Boltzmann equation. The proposed method is valid for both gas and liquid flows. A discrete flux scheme (DFS) is used to derive the governing equations for two distribution functions; one for mass and another for thermal energy. These equations are derived by considering an infinitesimally small control volume with a velocity lattice representation for the distribution functions. The zero-order moment equation of the mass distribution function is used to recover the continuity equation, while the first-order moment equation recovers the linear momentum equation. The recovered equations are correct to the first order of the Knudsen number(Kn);thus, satisfying the continuum assumption. Similarly, the zero-order moment equation of the thermal energy distribution function is used to recover the thermal energy equation. For aerodynamic flows, it is shown that the finite difference solution of the DFS is equivalent to solving the lattice Boltzmann equation (LBE) with a BGK-type model and a specified equation of state. Thus formulated, the DFS can be used to simulate a variety of aerodynamic and hydrodynamic flows. Examples of classical aeroacoustics, compressible flow with shocks, incompressible isothermal and non-isothermal Couette flows, stratified flow in a cavity, and double diffusive flow inside a rectangle are used to demonstrate the validity and extent of the DFS. Very good to excellent agreement with known analytical and/or numerical solutions is obtained; thus lending evidence to the DFS approach as an alternative to solving the Navier-Stokes equations for fluid flow simulations.
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Aliiev, Elchyn, Ihor Babyn i Serhiy Sokol. "NUMERICAL SIMULATION OF THE PROCESS OF AERODYNAMIC SEPARATION OF FINE-GRAINED BULK MATERIAL". ENGINEERING, ENERGY, TRANSPORT AIC, nr 1(120) (1.05.2023): 5–13. http://dx.doi.org/10.37128/2520-6168-2023-1-1.
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Various methods can be used to numerically simulate the aerodynamic separation of fine-grained bulk material, including discrete element methods, finite element methods, and bounded domain methods. In all these methods, these equations are solved numerically, and the results are used to determine the trajectories and velocities of air and particles. The Discrete Element Method (DEM), on the basis of which the study will be conducted, is designed for modeling the granular flow of materials. The purpose of the research is to simulate the movement of fine-grained loose material under the influence of air flow and calculate the parameters of its aerodynamic separation in the Simcenter STAR-CCM+ software package. The following were selected as physical models: gas, two-dimensional, separated flow, gradients, ideal gas, isothermal fluid energy equation, unsteady implicit, turbulent, Reynolds averaging of the Navier-Stokes equation, K-Epsilon turbulence model, admissible two-layer K-Epsilon, wall distance, double layer for any y+, gravity, Lagrangian multiphase, DEM discrete element model, multiphase interaction. As a result of the numerical simulation of the movement of fine-grained loose material under the influence of the air flow in the Simcenter STAR-CCM+ software package, the distribution of their components in the area of the separator was constructed. The following parameters were adopted as research factors: the diameter of the particles of the liquid fraction and impurities d, the particle supply speed f, the air flow speed v. Based on the results of the processing of the obtained data set in the Wolfram Cloud software package, the patterns of changes in the position of the intersection line of the distribution of two fractions (distance x) and the content of impurities δ in the liquid zone of separation from research factors were established. The presented detailed method of numerical modeling can be used to study other methods of separation of fine-grained loose materials.
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Qu, Yong Lei, Shi Bu i Bo Wan. "A 3D Numerical Investigation on Droplets Distribution in a Wave-Plate Separator". Advanced Materials Research 842 (listopad 2013): 522–29. http://dx.doi.org/10.4028/www.scientific.net/amr.842.522.
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The gas-liquid flow in a wave-plate separator is extremely complex due to its three-dimensional characteristic. Numerical simulation accomplished by former investigators using two-dimensional model may be appropriate for the iteration of pressure drop, but they were far from accurate in prediction of removal efficiency. To fill the gap, a three dimensional geometrical model of wave-plate separator is set up in this paper, RNG k-ε model is employed to compute the gas phase flow field, and the droplet trajectories were predicted applying the Lagrangian method. The turbulent dispersion of droplets were simulated by discrete random walk model. Using the assumption of a constant liquid loading of gas flow, simulation were accomplished for six different inlet velocities and two different droplet sizes. The influence pattern of gravity together with gas velocity on droplets distribution and the overall removal efficiencies were obtained.
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Anderson, Caitlin E., Toan Huynh, David J. Gasperino, Luis F. Alonzo, Jason L. Cantera, Stephen P. Harston, Helen V. Hsieh i in. "Automated liquid handling robot for rapid lateral flow assay development". Analytical and Bioanalytical Chemistry 414, nr 8 (29.01.2022): 2607–18. http://dx.doi.org/10.1007/s00216-022-03897-9.
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AbstractThe lateral flow assay (LFA) is one of the most popular technologies on the point-of-care diagnostics market due to its low cost and ease of use, with applications ranging from pregnancy to environmental toxins to infectious disease. While the use of these tests is relatively straightforward, significant development time and effort are required to create tests that are both sensitive and specific. Workflows to guide the LFA development process exist but moving from target selection to an LFA that is ready for field testing can be labor intensive, resource heavy, and time consuming. To reduce the cost and the duration of the LFA development process, we introduce a novel development platform centered on the flexibility, speed, and throughput of an automated robotic liquid handling system. The system comprises LFA-specific hardware and software that enable large optimization experiments with discrete and continuous variables such as antibody pair selection or reagent concentration. Initial validation of the platform was demonstrated during development of a malaria LFA but was readily expanded to encompass development of SARS-CoV-2 and Mycobacterium tuberculosis LFAs. The validity of the platform, where optimization experiments are run directly on LFAs rather than in solution, was based on a direct comparison between the robotic system and a more traditional ELISA-like method. By minimizing hands-on time, maximizing experiment size, and enabling improved reproducibility, the robotic system improved the quality and quantity of LFA assay development efforts. Graphical abstract
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Hu, X., i A. M. Jacobi. "The Intertube Falling Film: Part 1—Flow Characteristics, Mode Transitions, and Hysteresis". Journal of Heat Transfer 118, nr 3 (1.08.1996): 616–25. http://dx.doi.org/10.1115/1.2822676.
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When a liquid film falls from one horizontal tube to another below it, the flow may take the form of discrete droplets, jets, or a continuous sheet; the mode plays an important role in the wetting and heat transfer characteristics of the film. Experiments are reported that explore viscous, surface tension, inertial, and gravitational effects on the falling-film mode transitions. New flow classifications, a novel flow regime map, and unambiguous transition criteria for each of the mode transitions are provided. This research is part of an overall study of horizontal-tube, falling-film flow and heat transfer, and the results may have important implications on the design and operation of falling-film heat exchangers.
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ZHURAVLEVA, L. A., I. A. POPKOV, АLDIAB ANAS АLDIAB ANAS i HEIRBEIK BASSEEL HEIRBEIK BASSEEL. "Studies of flow characteristics in pressure pipelines of irrigation systems with discrete fluid sampling". Prirodoobustrojstvo, nr 5 (2022): 100–104. http://dx.doi.org/10.26897/1997-6011-2022-5-100-104.
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The purpose of the experiments is to study the characteristics of the flow in the pressure pipelines of irrigation systems with discrete liquid selection. The investigations have confi rmed a slight increase in the head along the perforated pipeline during withdrawal of the fluid, which is explained by the transition of kinetic energy to potential energy. Theoretical studies of the fluid flow with a flow rate variable along the length of the pipeline made it possible to obtain dependences that describe the characteristics of the flow in the presence of both uniform and non-uniform installation of drains along the pipeline and pressure losses, taking into account the discretenessparameter, which takes into account the number of outlets per a unit of the length, i.e. frequencyof setting. To clarify the coeffi cient of the flow disconnection, the studies were carried out, the results of which showed the independence of the ratio of the speeds of the main flow and the flow rate of the jet from the diameter of the outlet holes. The coefficient of disconnection of the flow is in the range of values from 0.66 to 0.87. The results of experimental studies allow us to conclude that the parameter of flow discreteness decreases with an increase in the number of drains. The value of the value of head losses in discrete withdrawalwas determined by the value of head losses with uniform withdrawal of the fluid flow, taking into account the discreteness parameter. The obtained calculated values are well confi rmed by the results of experimental studies.
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Tai, Zhongxu, Dongying Ju, Susumu Sato i Kenzo Hanawa. "Discrete Coating of CNT on Carbon Fiber Surfaces and the Effect on Improving the Electrochemical Performance of VRFB Systems". Coatings 11, nr 6 (18.06.2021): 736. http://dx.doi.org/10.3390/coatings11060736.
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Carbon fiber, as an electrode material, has been widely used in all-vanadium liquid flow batteries. In order to further reduce the size of the all-vanadium storage system, it is imperative to increase the current density of the battery and to achieve high conductivity and large electrostatic capacitance. The graphitization of the electrode material and the improvement in the specific surface area of the electrode surface also greatly affect the performance of all-vanadium redox liquid flow batteries. Therefore, in this paper, carbon nanotubes (CNTs) with a small diameter and a large specific surface area were coated on the electrode surface of the VRFB system by the dispersion method to improve the cell performance. The performance of the surface-modified electrode was also verified by Raman spectroscopy, XRD and SEM surface observations and charge/discharge experiments.
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Qiu, Liu-Chao, i Yu Han. "3D Simulation of Self-Compacting Concrete Flow Based on MRT-LBM". Advances in Materials Science and Engineering 2018 (2018): 1–8. http://dx.doi.org/10.1155/2018/5436020.
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A three-dimensional multiple-relaxation-time lattice Boltzmann method (MRT-LBM) with a D3Q27 discrete velocity model is applied for simulation of self-compacting concrete (SCC) flows. In the present study, the SCC is assumed as a non-Newtonian fluid, and a modified Herschel–Bulkley model is used as constitutive mode. The mass tracking algorithm was used for modeling the liquid-gas interface. Two numerical examples of the slump test and enhanced L-box test were performed, and the calculated results are compared with available experiments in literatures. The numerical results demonstrate the capability of the proposed MRT-LBM in modeling of self-compacting concrete flows.
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Cui, Xinjun, Matthew Harris, Martin Howarth, Daisy Zealey, Reegan Brown i Jonny Shepherd. "Granular flow around a cylindrical obstacle in an inclined chute". Physics of Fluids 34, nr 9 (wrzesień 2022): 093308. http://dx.doi.org/10.1063/5.0101694.
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Shock waves and granular vacua are important phenomena for studying the behavior of granular materials due to the dramatic change in flow properties across shock wave and the particle-free feature at the boundary of granular vacuum. In this paper, we use experiment and numerical simulation to study the granular free-surface flow past a cylindrical obstacle in an inclined chute, where the time-dependent development of the granular flow impacting the obstacle is analyzed at both microscopic and macroscopic scales using the discrete element method (DEM) and the depth-averaged granular model, respectively. Using high-speed camera results as a benchmark solution, the shock solutions are compared between experiment and simulation. The DEM simulation shows better agreement for its shock formation as it is capable of capturing solid, liquid, and gas behaviors for the shock region, while the depth-averaged model provides closer and simpler agreement for the jump solution across the shock. It is shown from the experiment and simulation that the granular shock wave can give rise to a solid–liquid–gas behavior following the propagation of the flow around the obstacle, where, at the front of the obstacle, the shock region can be regarded as a solid regime as the flow becomes stationary during the primary course of the granular flow. With the flow propagating to the downstream, the shock region extends significantly and exhibits strong liquid and gas behavior. Another mixed liquid and gas behavior of granular flow is also observed following the appearance of the granular vacuum, where a localized [Formula: see text]-rheology is shown to be effective in resolving the vacuum boundary in the numerical simulation.