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Artykuły w czasopismach na temat "Discrete Liquid Flow"
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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.
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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.
Rozprawy doktorskie na temat "Discrete Liquid Flow"
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Fry, Benjamin. "Modélisation multi-échelle d'un lit granulaire entraîné par un écoulement cisaillé". Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0132.
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Dans cette thèse, on étudie le transport granulaire par charriage en régime établi d’un lit de grains soumis à un écoulement de Couette laminaire pour un rapport de densité fluide-grain de 2.5 et une gamme de nombre de Reynolds particulaire, Re p [0.1, 10], et de nombre de Shields, [0.1,0.7]. Toutes les échelles de cet écoulement diphasique (à l’exception des effets de lubrification) sont décrites via la résolution numérique des équations de Navier-Stokes en prenant en compte la présence des particules par une méthode de frontières immergées (IBM) couplée à un solveur granulaire (méthode des éléments discrets - DEM) qui résout les équations de Newton pour chaque particule ainsi que les contacts et frottements entre grains (résolution à l’échelle microscopique). Un changement d’échelle est ensuite effectué afin d’obtenir une description de l’écoulement via des champs continus équivalents (description à l’échelle mésoscopique). Les simulations IBM-DEM permettent de quantifier chacun des termes du modèle dit mésoscopique et de caractériser la rhéologie de chaque phase ainsi que du mélange. On effectue finalement un second changement d’échelle afin de réduire l’écoulement de grains observé à une singularité, qui correspond à une condition limite du point de vue de l’écoulement du fluide. Cette condition est du type de Navier. Les simulations IBM-DEM montrent que la longueur dite de glissement "équivalente" est directement proportionnelle au nombre de ShieldsIn this work, we consider the steady transport of a granular medium by a laminar Couette flow for a fixed density ratio of 2.5 and a range of particle Reynolds number, Re p [0.1, 10], and Shields number [0.1, 0.7]. All scales of this two-phase flow are captured (except for the lubrication effects). By solving the Navier-Stokes equations, taking into account the presence of particles using an Immersed Boundary Method (IBM) coupled to a granular solver (Discrete Elements Method - DEM) which solves the Newton equations for each particle, in particular grain-grain interactions (resolution at the microscopic scale). Up-scaling is then performed to describe the flow via equivalent continuous quantities (description at the mesoscopic scale). IBM-DEM simulations allow to quantify all the terms of the so-called mesoscopic model and to characterize the rheology of each phase and that of the equivalent mixture. A second up-scaling is finally performed to reduce the granular flow to a singularity, which corresponds to a boundary condition from the fluid view point. The boundary condition is of Navier’s type. The IBM-DEM simulations suggest that the corresponding "equivalent" slip-lenght scales as
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Chang, Wei-Tze, i 張慰慈. "Parallel Discrete Element Simulation and Its Application to the Study of Solid-Liquid Flow Behavior". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/90428783048126841722.
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博士國立臺灣大學
土木工程學研究所
97
In recent years the widespread use of the Discrete Element Method (DEM) in engineering has generated increasing research interest across a variety of fields. As a result of rapid and continuing developments in computer science, DEM is now being applied to the modeling of physical phenomena and engineering problems of ever-increasing complexity. Solid-liquid flow behavior simulation is one ubiquitous application. However, dynamic behavior in such systems is difficult to predict due to complex interactions at the solid-liquid interface, which invoke considerable computational overhead. Since the method is constrained by contemporary processing power, an efficient Discrete Element Simulation (DES) system is needed for solving large-scale solid-liquid interaction problems. This paper undertakes to develop and apply such a system in the simulation of both Self-Compacting Concrete (SCC) and wet granular flow behavior. Three strategies are implemented to optimize existing DES procedures for computational speed; the result is an in-housed parallel DES system, KNIGHT&ANNE/IRIS 2.0 developed specifically for accelerated performance in solid-liquid flow simulation. Several numerical benchmarks are applied to both shared and distributed-memory platforms, indicating substantial performance improvements. A two-phase model is then developed for simulating SCC flow behavior. Various rheological experiments - the V-funnel flow test and the L-shaped box test - are modeled from packing to flowing, and DES handling of the simulation is shown to provide an adequate representation of empirical data. This comparison is also used to propose corresponding DES parameter values and ranges for simulation of SCC and mortar flow. A liquid-modified interaction model is proposed for the simulation of wet granular systems, and tested on both wet and dry particulate flows down an inclined channel. The level of congruence found between simulated and empirical data sets confirms the physical model to be reasonably accurate.
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Arunchaitanya, Gadi Venkat. "A Fundamental Investigation Of Discrete Liquid, Gas And Fines Flow In A Random Packed Bed Along With Applications". Thesis, 2023. https://etd.iisc.ac.in/handle/2005/6177.
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The discontinuous nature of liquid flow in a random packed bed is observed in many chemical engineering and metallurgical applications like blast furnace and heap leaching. So, to model the liquid flow in these systems, the discrete nature of the liquid flow should be taken into consideration. Moreover, the effect of gas flow on the particles and liquid phase of the packed bed, taking into account the random nature of the bed and the discrete nature of the liquid, is lacking. Therefore, fundamental understanding of the liquid-solid-gas interactions in a random bed is important to improve the processes.
To understand the effect of gas-solid interaction, a slow-moving packed bed, inside the reactor, has been considered. Particles are discharged from the bottom and gas is injected laterally. The gas flow has been modelled using continuum-based fluid flow equations. It is found that gas flow is not symmetric inside the reactor due to significant variation in void sizes inside the bed. This along with gas variation also affects the residence time of each particle inside the bed.
This work is extended to the liquid flow in random bed using Discrete Liquid Flow (DLF) theory. A novel graph-based recursive Depth First Search (DFS) algorithm is developed to find the shape and size of voids in the random bed. The liquid flow behaviour has been studied in various conditions, like changing the packing size and bed height. This study confirms that the bed topology plays an important role in dictating the liquid flow behavior in a randomly packed bed. Using the DLF, DFS, the various phenomena, which occur in a multiphase flow packed bed, such as rupturing of rivulets, liquid hysteresis have been understood and explained fundamentally.
The study is further extended to heap leaching process, where the liquid flows as droplets and rivulets due to very low liquid flow rates. The liquid flow behaviour is studied in terms of tortuosity, liquid distribution, breakthrough time, contact angle etc. The study shows that heap leaching processes can be modelled in more accurate and deterministic way using DLF theory along with DFS algorithm by avoiding the uncertain experimental parameters (like bed permeability etc).
Finally, the flow behaviour of the liquid phase in a random packed bed is studied, taking into account the movement of particles due to the lateral gas and fines injection. The deviation of the liquid path due to the gas and fines drag is also captured. It is found that the deviation of the liquid path is higher for the larger particle sizes.
Części książek na temat "Discrete Liquid Flow"
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Mahdavi, M., M. Sharifpur i J. P. Meyer. "Solid-Liquid Two-Component Flow: Discrete Phase and Mixture Approaches for Nanoscale Heat Transfer". W Handbook of Multiphase Flow Science and Technology, 1–54. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-4585-86-6_25-1.
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Shilko, Evgeny V., Alexey Yu Smolin, Andrey V. Dimaki i Galina M. Eremina. "Particle-Based Approach for Simulation of Nonlinear Material Behavior in Contact Zones". W Springer Tracts in Mechanical Engineering, 67–89. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-60124-9_4.
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AbstractMethods of particles are now recognized as an effective tool for numerical modeling of dynamic mechanical and coupled processes in solids and liquids. This chapter is devoted to a brief review of recent advances in the development of the popular particle-based discrete element method (DEM). DEM is conventionally considered as a highly specialized technique for modeling the flow of granular media and the fracture of brittle materials at micro- and mesoscopic scales. However, in the last decade, great progress has been made in the development of the formalism of this method. It is largely associated with the works of the scientific group of Professor S. G. Psakhie. The most important achievement of this group is a generalized formulation of the method of homogeneously deformable discrete elements. In the chapter, we describe keystones of this implementation of DEM and a universal approach that allows one to apply various rheological models of materials (including coupled models of porous fluid-saturated solids) to a discrete element. The new formalism makes possible qualitative expansion of the scope of application of the particle-based discrete element technique to materials with various rheological properties and to the range of considered scales form microscopic to macroscopic. The capabilities of this method are especially in demand in the study of the features of contact interaction of materials. To demonstrate these capabilities, we briefly review two recent applications concerning (a) the effect of adhesive interaction on the regime of wear of surface asperities under tangential contact of bodies and (b) the nonmonotonic dependence of the stress concentration in the neck of the human femur on the dynamics of hip joint contact loading.
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Gouesbet, G., A. Berlemont i P. Desjonquéres. "Prediction and Simulation of the Behaviour of Discrete Particles Transported by Turbulent Flows: a Review Paper". W Chemical Reactivity in Liquids, 607–16. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-1023-5_53.
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Tsutsumi, T., S. Takeuchi i T. Kajishima. "Effect of Solid And Liquid Heat Conductivities on Two-Phase Heat and Fluid Flows". W Discrete Element Modelling of Particulate Media, 21–29. The Royal Society of Chemistry, 2012. http://dx.doi.org/10.1039/bk9781849733601-00021.
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Liquid-solid two-phase flow with heat transfer is simulated, and the effects of temperature gradient within a solid object and particle mobility on heat transfer are studied. The interaction between fluid and particles is considered with our original immersed solid approach on a rectangular grid system. A discrete element model with soft-sphere collision is applied for particle-particle interaction. Governing equation of temperature is time-updated with an implicit treatment for the diffusion term, which enables stable simulation with particles of very high/low ratios of heat conductivity (from 1/1000 to 1000) to fluid. The local heat flux at the fluid-solid interface is carefully discretised and incorporated into the implicit scheme of temperature. The method is applied to a 2-D confined flow including multiple particles under a high Rayleigh number condition. Heat transfer and particle behaviours are studied for different ratios of heat conductivity (solid to liquid) and solid volume fractions. For a relatively low solid volume fraction, a transition of particulate flow pattern is observed depending on the heat conductivity ratio; the cases with high ratios of heat conductivities exhibit simple (single or double) circulating flows, whereas low heat conductivity ratio causes complicated flow patterns involving multiple circulation of particles, resulting in low Nusselt number. The above simulation results, together with the heat transfer properties under a near-packed condition, highlight the effect of temperature distributions within the particles and liquid.
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Artoni, R., F. Gabrieli, A. Santomaso i S. Cola. "Effect of the Pendular State on the Collapse of Granular Columns". W Discrete Element Modelling of Particulate Media, 95–102. The Royal Society of Chemistry, 2012. http://dx.doi.org/10.1039/bk9781849733601-00095.
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Granular materials exhibit special phase transitions between different mechanical states. They behave like solids or fluids when particular conditions occur. Generally, the presence of water in the granular medium greatly affects mechanical stability, as well as jamming and blockage in dynamic phenomena, even in very small amounts. In this work the triggering and the stopping of flow was studied with regards to granular column collapse experiments. Glass beads of different grain-size were mixed with liquids of different surface tension values. The amount of liquid was varied from 0 to 5% in order to maintain the pendular state. The material was first poured in a rectangular box and then allowed to flow by removing a lateral wall. The movement of the mass was captured by a high-speed CCD camera. Repose angles, run-out and slope height were measured in order to explore the effect of the different initial dry and wet conditions on the profile evolution. DEM numerical simulations were also carried out in a 1:1 scale reproducing the same experimental configuration and conditions. The classical Discrete Element model with spring dashpot at the normal contact was coupled with a capillary attraction force based on the minimum energy approach. Using DEM, the effect of liquid content and liquid surface tension were also evaluated. A good agreement between experiments and DEM simulations was found with respect to the kinematic and the final slope profile. In particular, both the techniques highlight the effect of the liquid that reduces the run-out distance and time even for small liquid contents. This work demonstrates the suitability of the DEM approach for the study of wet granular materials in static as well as in dynamic conditions.
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Florea, Larisa, Dermot Diamond i Fernando Benito-Lopez. "Opto-Smart Systems in Microfluidics". W Research Perspectives on Functional Micro- and Nanoscale Coatings, 265–88. IGI Global, 2016. http://dx.doi.org/10.4018/978-1-5225-0066-7.ch010.
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The possibility of using photo-stimulus to control flow in microfluidics devices is very appealing as light can provide contactless stimulation, is biocompatible and can be applied in a non-invasive and highly precise manner. One of the most popular ways to achieve photo-control flow in microfluidic channels is throughout the use of photo-responsive molecules. We review here the different principles and strategies of using photo-responsive molecules to induce or control liquid motion using light, which include the use of photo-controlled polymeric actuators, photo-sensitive coatings, or photo-sensitive surfactants. We further analyse the capability of these approaches to induce flow control throughout the photo-operation of valves, photo-control of electro-osmotic flows or photo-manipulation of discrete microliter-sized droplets.
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Obodovych, Oleksandr, i Olesya Stepanova. "NUMERICAL SIMULATION OF THE PROCESSES OF HYDRODTNAMICS AND HEAT TRANSFER PROCESSES IN ROTOR-PULSATION APPARATUS". W Traditional and innovative approaches to scientific research: theory, methodology, practice. Publishing House “Baltija Publishing”, 2022. http://dx.doi.org/10.30525/978-9934-26-241-8-5.
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The development of energy-saving technologies that meet the modern requirements of product production is based on the development of new concepts, conducting comprehensive scientific research, and a detailed study of the essence of physical phenomena, which determines the possibility of purposeful management of the technological process and ensuring optimal conditions for its implementation. In the existing devices for the preparation of mixtures, grinding methods are used in hammer crushers and mills, which requires significant expenditure of mechanical (electrical) energy. Therefore, it is necessary to develop devices with a high degree of influence on the processed environment, which increases productivity and reduces energy consumption in technological processes. Such devices include rotary-pulsation devices, the principle of operation of which is based on the method of discrete-pulse energy input. The basis of this method is the multifactorial influence on the processed liquid homogeneous or heterogeneous environment, consisting of pressure pulsations, changes in the liquid flow rate, intense cavitation, developed turbulence, rigid cumulative impact, as well as high shear forces. The current task in this work is the study of the impact of discrete-pulse energy input mechanisms that take place in rotary-pulsation devices during the processing of heterogeneous media, as well as the development of new designs of devices of the specified type to obtain high-quality products. Therefore, the work is devoted to the development of a new design of the rotor-pulsation apparatus for the preparation of liquid mixtures, the principle of which is the use of a working chamber with a rotor and a stator, which have holes of different configurations. The purpose of the study is to conduct a comprehensive analysis of kinematic and dynamic characteristics and establish the features of discrete-pulse energy input during the dispersion of mixtures in a rotary-pulsation apparatus and to develop, on this basis, energy-saving technology and equipment for their preparation. Numerical modeling and experimental research of the processes of hydrodynamics and heat transfer in the mixture during its preparation were carried out. The working chamber of the device consists of a cylindrical rotor and stator containing round and rectangular perforated holes. The mathematical model includes the two- or three-dimensional Navier-Stokes equations, the κ-ε transport equation of the turbulence model, and the energy equation. Factors that affect the processes of deformation and destruction of dispersed particles in heterogeneous media processed in rotary-pulsation devices are pressure pulsations, as well as normal and tangential stress pulsations that occur in the flow when it passes through the working zone of the device. As a result of numerical studies, the fields of velocities, pressures and temperatures of the studied media were found, and the most optimal geometric characteristics of the working chamber of the rotary-pulsation apparatus were determined. Based on the obtained results of numerical simulation, the designs of the rotor-pulsation apparatus will be selected, which will be used for the production of industrial research samples of this device.
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J.K. Wood, Robert, i Alexander D.C. Cook. "Erosion-Corrosion in Pipe Flows of Particle-Laden Liquids". W Slurry Technology - New Advances [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.107231.
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The transmission of particle-bearing liquids in pipes has motivated continuing research into erosion mechanisms and the distribution of erosion rates over wetted surfaces. This chapter covers these initiatives with particular reference to erosion-corrosion modelling within bends and straight sections of cylindrical pipes manufactured in a variety of materials and transporting a variety of liquids. Erosion-corrosion modelling techniques such as submerged slurry jets and rotating cylinder electrodes have been used to study factors influencing material degradation. Improvements in computational fluid dynamics (CFD), such as the development of a moving deforming mesh (MDM) have improved the accuracy of CFD models in predicting pipe wall erosion rates. Combined discrete phase tracking approaches such as the CFD-DPM-DEM (discrete phase-discrete element model) have helped improve computational efficiency. Wall impact erosion models are calibrated using laboratory scale tests. Validation of CFD models using full-scale test data is rare, meaning their accuracy is still largely unreported. Material testing has helped to identify the resilience of prospective pipeline materials to erosion-corrosion, while modifications to internal geometry and pipe section have shown potential to improve erosion-corrosion resistance.
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Erman, Burak, i James E. Mark. "Critical Phenomena and Phase Transitions in Gels". W Structures and Properties of Rubberlike Networks. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195082371.003.0009.
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The term “gel” has been used in a wide variety of contexts, and there have been difficulties in reaching an all-inclusive, workable definition for it. Perhaps the simplest way to proceed is to list some of its most important characteristics: It is a solidlike material that when deformed responds in the manner of a typical elastic body, but generally with a very small modulus. If it does show plastic flow, then this occurs above a threshold value of the stress, with full recoverability below this limit. It typically consists of two or more components: one a liquid in substantial quantity, and the other generally a polymeric network. One of the most direct ways of obtaining a gel is to place a network into a solvent known to be capable of dissolving the network chains in the absence of cross-links. In fact, a unique property of a highly extensible elastomer (resulting from a low degree of cross-linking) is its ability to swell greatly when exposed to a good solvent. A gel with less than 10-6 mol cm-3 of cross-links, for example, may increase its volume more than thousandfold when immersed in a suitable solvent. The extent to which such a network will swell depends specifically not only on the degree of cross-linking, but also on the interactions between the chains and the solvent. While the degree of cross-linking is established during the preparation of a network, the extent of the interaction of chains and solvent may be modified as desired, and therefore the degree of swelling may be controlled. A gel can be made to swell or shrink continuously by changing the quality of the solvent with which it is in contact. Alternatively, it may go through critical conditions and, in fact, can exhibit phase transitions, depending on the type of the polymer-solvent interaction and the extent of cross-linking. The discrete shrinkage of the gel, by changing the polymer-solvent interaction parameter, is a volume phase transition similar to the gas-liquid transition of a condensing gas. The possibility of such phase transitions was, notably, first discussed by Dusek and collaborators many years ago. Their treatment was confined to nonionic networks.
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Dezeuze, Anna. "Joins in the age of ‘liquid modernity’". W Almost Nothing. Manchester University Press, 2017. http://dx.doi.org/10.7228/manchester/9780719088575.003.0005.
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This chapter provides a reading of precarious practices developed in the 1990s by artists Francis Alÿs, Gabriel Orozco, Thomas Hirschhorn and Martin Creed as both responses to forms of aggressive capitalism that had become widespread since the 1980s, and reactions to some of the more visible art practices that had emerged during that decade. Zygmunt Bauman’s 2000 analysis of the ‘liquid’ characteristics of contemporary capitalism is shown to extend Arendt’s earlier discussion of the modern human condition in its emphasis on ever-faster cycles of consumer gratification at the expense of durable products and stable social relations. This chapter demonstrates some of the ways in which 1990s practices extended the dematerialisation of 1960s assemblage and ‘borderline’ practices, through explorations of a ‘join’ between art and the world, as Martin Creed called it, through discreet interventions (Francis Alÿs, Gabriel Orozco), or sprawling assemblages (Thomas Hirschhorn). Most importantly, this join may serve as a rub in the smooth global flows of capital.
Streszczenia konferencji na temat "Discrete Liquid Flow"
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Xu, Zhiliang, Roman Samulyak, James Glimm i Xiaolin Li. "Discrete Bubble Modeling of Unsteady Cavitating Flow". W ASME 2006 2nd Joint U.S.-European Fluids Engineering Summer Meeting Collocated With the 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/fedsm2006-98147.
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A discrete vapor bubble model is developed to simulate the unsteady cavitating flows. The mixed vapor-liquid mixture is modeled as a system of pure phase domains (vapor and liquid) separated by free interfaces. On the phase boundary, a numerical solution for the phase transition is developed for compressible flows.
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Abbas, Micheline, Martin Van der Hoef, Onno Bokhove, Hans Kuipersd, Liejin Guo, D. D. Joseph, Y. Matsumoto, Y. Sommerfeld i Yueshe Wang. "Discrete element study of liquid-solid slurry flows through constricted channels". W THE 6TH INTERNATIONAL SYMPOSIUM ON MULTIPHASE FLOW, HEAT MASS TRANSFER AND ENERGY CONVERSION. AIP, 2010. http://dx.doi.org/10.1063/1.3366386.
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Sekar, Jayanth, Arvind Rao, Sreedhar Pillutla, Allen Danis i Shih-Yang Hsieh. "Liquid Jet in Cross Flow Modeling". W ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26124.
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All key combustor performance & operability characteristics like emissions, exit profile, durability, LBO etc. have a dependence on spray quality. Hence it is important to accurately predict spray characteristics for accurate combustor modeling. In this paper, a CFD based liquid jet in cross flow spray modeling approach adopted at GE Aviation is presented. Liquid jet in cross flow is a complex phenomenon that broadly involves jet trajectory evolution, surface breakup, column fracture and dispersion of secondary droplet particles. A two-phase steady state Volume of Fluid (VOF) approach is used to predict the liquid jet trajectory. A combination of output from VOF and empirical correlations (Sallam et. al; Oda et. al) is used to predict droplet distribution that includes diameter, velocity components and mass flow rate. Surface breakup is modeled by injecting droplets along the leeward surface of the liquid jet with spanwise perturbation to capture the transverse spread. Jet column breakup is modeled by injecting droplets including effects of unsteady fluctuations empirically to mimic the column fracture behavior. Discrete particles are then transported in a lagrangian frame coupled with secondary breakup of droplets. This approach has been validated on a benchmark quality dataset with an average SMD (Sauter Mean Diameter) error of ∼6 microns and is being used on Gas Turbine combustor fuel-air mixing devices employing liquid jet in cross flow atomizers.
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Choi, Chang-Hwan, Joonwon Kim i Chang-Jin Kim. "Nanoturf Surfaces for Reduction of Liquid Flow Drag in Microchannels". W ASME 2004 3rd Integrated Nanosystems Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/nano2004-46078.
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We report nano-engineered surfaces (NanoTurf), designed to make various micro- and nano-fluidic devices and systems less frictional for liquid flows, and describe microchannels made with such a surface. While our group has reported a dramatic (> 95%) drag reduction of discrete droplets flowing in a space between two parallel-plates covered with “random” nano-posts created by the “black silicon method” [1], this paper describes various nanofabrication techniques, including those capable of “designing” nanostructures with not only a good control of pattern sizes and periods but also practical manufacturability to be embedded in various micro- and nano-fluidic devices and systems. Microchannels are developed using the designed nanostructure surfaces and used for continuous flow tests.
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Strongin, Mikhail P. "CFD Simulation of Water Flow Mixing With Discrete Phase in a Pump". W ASME 2013 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/fedsm2013-16184.
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The mixing process is very common in many industrial applications. In some cases, two or more liquids or discrete phase (DP) set on the pump inlet. Liquid mixture is often occurred in sanitation and agriculture applications and mixture of water with DP (such as sand) are met in the case of water transportation from natural sources (rivers, wells, etc.). DP distribution in the centrifugal pump is the subject of this study. Full pump geometry is considered, due to unsymmetrical nature of volute of the pump. Turbulence k-ε closure model and Lagrangian discrete phase model has been used for most simulations. It was found that smaller particles trap inside the pump for longer time than larger ones. The distribution of the bigger diameter particles on the outlet is more asymmetrical in comparison with particles of smaller diameter. Relatively large areas with very small particle concentrations can be observed. Particle distribution on the outlet for lighter particles demonstrates more uniformity.
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Manhartsgruber, Bernhard. "Instantaneous Liquid Flow Rate Measurement Utilizing the Dynamic Characteristics of Laminar Flow in Circular Pipes". W ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45613.
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The instantaneous measurement of transient flow rates is an important problem in many fluid power applications such as the investigation of the flow ripple generated by hydraulic pumps or the measurement of flow rate changes at the ports of fast switching valves. This paper deals with the utilization of the dynamic characteristics of laminar flow in circular pipes for the indirect measurement of flow rates. A discrete time state space realization of the transmission line dynamics is computed via inverse Laplace transform and an identification and model reduction method based on the singular value decomposition. This dynamic system is used for the computation of the flow rate at one end of a pipe section. Special attention is paid to the identification of the speed of sound and the dimensionless dissipation number of the pipe section, since exact knowledge of these parameters is crucial for the reliabilty of the measurement results.
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Takei, Masahiro, Yassin A. Hassan, J. Ortiz-Villafuerte i Tomomasa Uemura. "Modal Wavelets Analysis to Gas-Liquid Two Phase Flow PIV Images". W 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/icone14-89637.
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A modal wavelet transform, which overcomes the intrinsic data number limitation of power of two to conventional wavelet transform, has been applied to analysis of pseudo and real bubbly flow PIV images. The modal wavelet transform is compared with the discrete wavelet transform in order to select the best base function among Neumann, Dirichlet and Green function types base functions. Consequently, it is verified that Neumann type base function is the best because the correlation of Neumann type base function is the highest. From the result of wavelet analysis of the real bubbly flow PIV image, as the relative velocity is higher, the dominant eddy scale becomes smaller. The extraction modal wavelet level depends on the base function.
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Rahman, Muhammad M., i Santosh K. Mukka. "Confined Liquid Jet Impingement on a Plate With Discrete Heating Elements". W ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72408.
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The primary focus of this paper is the conjugate heat transfer during vertical impingement of a two-dimensional (slot) submerged confined liquid jet using liquid ammonia as the working fluid. Numerical model for the heat transfer process has been developed. The solid region has been modeled along with the fluid region as a conjugate problem. Discrete heat sources have been used to study the overall effect on convective heat transfer. Simulation of discrete heat sources was done by introducing localized heat fluxes at various locations and their magnitudes being varied. Simulations are performed for two different substrate materials namely silicon and stainless steel. The equations solved in the liquid region included the conservation of mass, conservation of momentum, and conservation of energy. In the solid region, only the energy equation, which reduced to the heat conduction equation, had to be solved. The solid-fluid interface temperature showed a strong dependence on several geometric, fluid flow, and heat transfer parameters. The Nusselt number increased with Reynolds number. For a given flow rate, a higher heat transfer coefficient was obtained with smaller slot width and lower impingement height. For a constant Reynolds number, jet impingement height and plate thickness, a wider opening of the slot provided higher average heat transfer coefficient and higher average Nusselt number. A higher average heat transfer coefficient was seen at a smaller thickness, whereas a thicker plate provided a more uniform distribution of heat transfer coefficient. Higher thermal conductivity substrates also provided a more uniform heat distribution.
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Zhang, Xinyu, i Goodarz Ahmadi. "Particle Effects on Gas-Liquid-Solid Flows". W ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-65695.
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A numerical simulation is carried out to study the role of particles in gas-liquid-solid flows in bubble columns. An Eulerian-Lagrangian model is used and the liquid flow is modeled using a volume-averaged system of governing equations, while motions of bubbles and particles are evaluated using Lagrangian trajectory analysis. It is assumed that the bubbles remain spherical. The interactions between bubble-liquid and particle-liquid are included in the study. The discrete phase equations include drag, lift, buoyancy, and virtual mass forces. Particle-particle interactions and bubble-bubble interactions are accounted for by the hard sphere model approach. The bubble coalescence is also included in the model. Neutrally buoyant particles are used in the study. A parcel approach is used and a parcel represents a certain number of particles of same size, velocity, and other properties. Variation of particle loading is modeled by changing the corresponding number of particles in every parcel. In a previous work, the predicted results were compared with the experimental data, and good agreement was obtained. The transient flow characteristics of the three-phase flow are studied and the effects of particle loading on flow characteristics are discussed. The simulations show that the transient characteristics of the three-phase flow in a column are dominated by time-dependent vortices. The particle loading can affect the characteristics of the three-phase flows and flows with high particle loading evolve faster.
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Yang, Hyunjin, Surya P. Vanka i Brian G. Thomas. "Hybrid Eulerian Eulerian Discrete Phase Model of Turbulent Bubbly Flow". W ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-70337.
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The Eulerian-Eulerian two-fluid model [1] (EE) is the most general model in multiphase flow computations. One limitation of the EE model is that it has no ability to estimate the local bubble sizes by itself. Thus, it must be complemented either by measurements of bubble size distribution or by additional models such as population balance theory or interfacial area concentration to get the local bubble size information. In this work, we have combined the Discrete Phase model (DPM) [2,8] to estimate the evolution of bubble sizes with the Eulerian-Eulerian model. The bubbles are tracked individually as point masses, and the change of bubble size distribution is estimated by additional coalescence and breakup modeling of the bubbles. The time varying bubble distribution is used to compute the local interface area between gas and liquid phase, which is used to estimate the momentum interactions such as drag, lift, wall lubrication and turbulent dispersion forces. This model is applied to compute an upward flowing bubbly flow in a vertical pipe and the results are compared with previous experimental work of Hibiki et al. [3]. The newly developed hybrid model (EEDPM) is able to reasonably predict the locally different bubble sizes and the velocity and void fraction fields. On the other hand, the standard EE model without the DPM shows good comparison with measurements only when the prescribed constant initial bubble size is accurate and does not change much.
Raporty organizacyjne na temat "Discrete Liquid Flow"
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Shmulevich, Itzhak, Shrini Upadhyaya, Dror Rubinstein, Zvika Asaf i Jeffrey P. Mitchell. Developing Simulation Tool for the Prediction of Cohesive Behavior Agricultural Materials Using Discrete Element Modeling. United States Department of Agriculture, październik 2011. http://dx.doi.org/10.32747/2011.7697108.bard.
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The underlying similarity between soils, grains, fertilizers, concentrated animal feed, pellets, and mixtures is that they are all granular materials used in agriculture. Modeling such materials is a complex process due to the spatial variability of such media, the origin of the material (natural or biological), the nonlinearity of these materials, the contact phenomenon and flow that occur at the interface zone and between these granular materials, as well as the dynamic effect of the interaction process. The lack of a tool for studying such materials has limited the understanding of the phenomena relevant to them, which in turn has led to energy loss and poor quality products. The objective of this study was to develop a reliable prediction simulation tool for cohesive agricultural particle materials using Discrete Element Modeling (DEM). The specific objectives of this study were (1) to develop and verify a 3D cohesionless agricultural soil-tillage tool interaction model that enables the prediction of displacement and flow in the soil media, as well as forces acting on various tillage tools, using the discrete element method; (2) to develop a micro model for the DEM formulation by creating a cohesive contact model based on liquid bridge forces for various agriculture materials; (3) to extend the model to include both plastic and cohesive behavior of various materials, such as grain and soil structures (e.g., compaction level), textures (e.g., clay, loam, several grains), and moisture contents; (4) to develop a method to obtain the parameters for the cohesion contact model to represent specific materials. A DEM model was developed that can represent both plastic and cohesive behavior of soil. Soil cohesive behavior was achieved by considering tensile force between elements. The developed DEM model well represented the effect of wedge shape on soil behavior and reaction force. Laboratory test results showed that wedge penetration resistance in highly compacted soil was two times greater than that in low compacted soil, whereas DEM simulation with parameters obtained from the test of low compacted soil could not simply be extended to that of high compacted soil. The modified model took into account soil failure strength that could be changed with soil compaction. A three dimensional representation composed of normal displacement, shear failure strength and tensile failure strength was proposed to design mechanical properties between elements. The model based on the liquid bridge theory. An inter particle tension force measurement tool was developed and calibrated A comprehensive study of the parameters of the contact model for the DEM taking into account the cohesive/water-bridge was performed on various agricultural grains using this measurement tool. The modified DEM model was compared and validated against the test results. With the newly developed model and procedure for determination of DEM parameters, we could reproduce the high compacted soil behavior and reaction forces both qualitatively and quantitatively for the soil conditions and wedge shapes used in this study. Moreover, the effect of wedge shape on soil behavior and reaction force was well represented with the same parameters. During the research we made use of the commercial PFC3D to analyze soil tillage implements. An investigation was made of three different head drillers. A comparison of three commonly used soil tillage systems was completed, such as moldboard plow, disc plow and chisel plow. It can be concluded that the soil condition after plowing by the specific implement can be predicted by the DEM model. The chisel plow is the most economic tool for increasing soil porosity. The moldboard is the best tool for soil manipulation. It can be concluded that the discrete element simulation can be used as a reliable engineering tool for soil-implement interaction quantitatively and qualitatively.
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Pullammanappallil, Pratap, Haim Kalman i Jennifer Curtis. Investigation of particulate flow behavior in a continuous, high solids, leach-bed biogasification system. United States Department of Agriculture, styczeń 2015. http://dx.doi.org/10.32747/2015.7600038.bard.
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Recent concerns regarding global warming and energy security have accelerated research and developmental efforts to produce biofuels from agricultural and forestry residues, and energy crops. Anaerobic digestion is a promising process for producing biogas-biofuel from biomass feedstocks. However, there is a need for new reactor designs and operating considerations to process fibrous biomass feedstocks. In this research project, the multiphase flow behavior of biomass particles was investigated. The objective was accomplished through both simulation and experimentation. The simulations included both particle-level and bulk flow simulations. Successful computational fluid dynamics (CFD) simulation of multiphase flow in the digester is dependent on the accuracy of constitutive models which describe (1) the particle phase stress due to particle interactions, (2) the particle phase dissipation due to inelastic interactions between particles and (3) the drag force between the fibres and the digester fluid. Discrete Element Method (DEM) simulations of Homogeneous Cooling Systems (HCS) were used to develop a particle phase dissipation rate model for non-spherical particle systems that was incorporated in a two-fluid CFDmultiphase flow model framework. Two types of frictionless, elongated particle models were compared in the HCS simulations: glued-sphere and true cylinder. A new model for drag for elongated fibres was developed which depends on Reynolds number, solids fraction, and fibre aspect ratio. Schulze shear test results could be used to calibrate particle-particle friction for DEM simulations. Several experimental measurements were taken for biomass particles like olive pulp, orange peels, wheat straw, semolina, and wheat grains. Using a compression tester, the breakage force, breakage energy, yield force, elastic stiffness and Young’s modulus were measured. Measurements were made in a shear tester to determine unconfined yield stress, major principal stress, effective angle of internal friction and internal friction angle. A liquid fludized bed system was used to determine critical velocity of fluidization for these materials. Transport measurements for pneumatic conveying were also assessed. Anaerobic digestion experiments were conducted using orange peel waste, olive pulp and wheat straw. Orange peel waste and olive pulp could be anaerobically digested to produce high methane yields. Wheat straw was not digestible. In a packed bed reactor, anaerobic digestion was not initiated above bulk densities of 100 kg/m³ for peel waste and 75 kg/m³ for olive pulp. Interestingly, after the digestion has been initiated and balanced methanogenesis established, the decomposing biomass could be packed to higher densities and successfully digested. These observations provided useful insights for high throughput reactor designs. Another outcome from this project was the development of low cost devices to measure methane content of biogas for off-line (US$37), field (US$50), and online (US$107) applications.