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NURBS-based DEM for non-spherical particles

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Particuology 2020年第2期18卷 65-76页

作者： Shiwen Liu feiguo chen Wei Ge Philippe Ricoux State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesP.O.Box 353Beijing 100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China Data Processing and Modeling TOTAL Scientific DivisionFrance

The discrete element method(DEM)is used to analyze complex practical granular systems;however,the representation of real shapes is an important consideration because behavior of non-spherical particles is unlike that of spherical particles both individually and *** this study,we use non-uniform rational basis-splines(NURBS)to describe the shapes of non-spherical particles and introduce a contact detection scheme based on quadratic convergence,to simulate the behaviors of elliptical *** simulation results are compared with those based on polygons,in terms of the shape description and contact treatment,to demonstrate the high accuracy and efficiency of NURBS-based DEM.

关键词： Non-spherical particle Discrete element method NURBS Facet-based DEM Granular system

Molecular dynamics simulation of complex multiphase flow on a computer cluster with GPUs

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Science China Chemistry 2009年第3期52卷 372-380页

作者： chen feiguo GE Wei LI JingHai State Key Laboratory of Multi-Phase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China Graduate University of Chinese Academy of Sciences Beijing 100039China

Compute Unified Device Architecture (CUDA) was used to design and implement molecular dynamics (MD) simulations on graphics processing units (GPU). With an NVIDIA Tesla C870, a 20-60 fold speedup over that of one core of the Intel Xeon 5430 CPU was achieved, reaching up to 150 Gflops. MD simulation of cavity flow and particle-bubble interaction in liquid was implemented on multiple GPUs using a message passing interface (MPI). Up to 200 GPUs were tested on a special network topology, which achieves good scalability. The capability of GPU clusters for large-scale molecular dynamics simulation of meso-scale flow behavior was, therefore, uncovered.

关键词： multiphase flow molecular dynamics CUDA GPU parallel computing

Eulerian–Lagrangian simulation of bubble coalescence in bubbly flow using the spring-dashpot model

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Chinese Journal of Chemical Engineering 2017年第3期25卷 249-256页

作者： Jing Xue feiguo chen Ning Yang Wei Ge State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesP.O.Box 353Beijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The Eulerian–Lagrangian simulation of bubbly flow has the advantage of tracking the motion of bubbles in continuous fluid, and hence the position and velocity of each bubble could be accurately acquired. Previous simulation usually used the hard-sphere model for bubble–bubble interactions, assuming that bubbles are rigid spheres and the collisions between bubbles are instantaneous. The bubble contact time during collision processes is not directly taken into account in the collision model. However, the contact time is physically a prerequisite for bubbles to coalesce, and should be long enough for liquid film drainage. In this work we applied the spring-dashpot model to model the bubble collisions and the bubble contact time, and then integrated the spring-dashpot model with the film drainage model for coalescence and a bubble breakage model. The bubble contact time is therefore accurately recorded during the collisions. We investigated the performance of the spring-dashpot model and the effect of the normal stiffness coefficient on bubble coalescence in the *** results indicate that the spring-dashpot model together with the bubble coalescence and breakage model could reasonably reproduce the two-phase flow field, bubble coalescence and bubble size distribution. The influence of normal stiffness coefficient on simulation is also discussed.

关键词： Bubble column Spring-dashpot model CoalescenceBreak-up Bubble size distribution

A study on periodic boundary condition in direct numerical simulation for gas–solid flow

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Chinese Journal of Chemical Engineering 2020年第1期28卷 236-241页

作者： Shiwen Liu Xiaowen Liu feiguo chen Limin Wang Wei Ge State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China

Direct numerical simulation(DNS) of gas–solid flow at high resolution has been carried out by coupling the lattice Boltzmann method(LBM) for gas flow and the discrete element method(DEM) for solid particles. However,the body force periodic boundary condition(FPBC) commonly used to cut down the huge computational cost of such simulation has faced accuracy concerns. In this study, a novel two-region periodic boundary condition(TPBC) is presented to remedy this problem, with the flow driven in the region with body force and freely evolving in the other region. With simulation cases for simple circulating fluidized bed risers, the validity and advantages of TPBC are demonstrated with more reasonable heterogeneity of the particle distribution as compared to the corresponding case with FPBC.

关键词： Direct numerical simulation Periodic boundary condition Two-region periodic boundary condition Gas–solid flow Heterogeneity

Pseudo-particle modeling for gas flow in microchannels

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Chinese Science Bulletin 2007年第4期52卷 450-455页

作者： WANG LiMin GE Wei chen feiguo State Key Laboratory of Multi-phase Complex System Institute of Process Engineering Chinese Academy of Sciences Beijing 100080 China Graduate University Chinese Academy of Sciences Beijing 100049 China

The velocity profiles and temperature distributions of gas flow in microchannels, for Knudsen numbers ranging from 0.01 to 0.20, are investigated with pseudo-particle modeling (PPM). It has been found that the velocity profiles are mainly affected by Knudsen number and the external force fields applied. When Knudsen number was increased, the slip velocities on the walls increased at the beginning, and then decreased. The temperature distributions were also significantly affected by the external force. The Darcy friction factor increased with increasing Knudsen number, and its variation with Mach number under increased Knudsen number was similar to the so-called premature laminar-turbulent transition observed in experiments.

关键词：微通道气体流动伪粒子模型努森数马赫数

Numerical investigation of granular flow similarity in rotating drums

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Particuology 2015年第5期13卷 119-127页

作者： Huabiao Qi Ji Xu Guangzheng Zhou feiguo chen Wei Ge Jinghai Li State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of Sciences University of Chinese Academy of Sciences

The theory of flow similarity has not been well established for granular flows, in contrast to the case for conventional fluids, owing to a lack of reliable and general constitutive laws for their continuum descrip- tion. A rigorous investigation of the similarity of velocity fields in different granular systems would he valuable to theoretical studies. However, experimental measurements face technological and physical problems. Numerical simulations that employ the discrete element method （DEM） may be an alterna- tive to experiments by providing similar results, where quantitative analysis could be implemented with virtually no limitation. In this study, the similarity of velocity fields is investigated for the rolling regime of rotating drums by conducting simulations based on the DEM and using graphics processing units. For a constant Froude number, it is found that the particle-to-drum size ratio plays a dominant role in the determination of the velocity field, while the velocity field is much more sensitive to some material properties than to others. The implications of these findings are discussed in terms of establishing theoretical similarity laws for granular flows.

关键词： Discrete element method Granular flow Similarity Rotating drum Scale up Graphics processing unit

Multi-scale HPC system for multi-scale discrete simulation—Development and application of a supercomputer with 1 Petaflops peak performance in single precision

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Particuology 2009年第4期7卷 332-335页

作者： feiguo chen Wei Ge Li Guo Xianfeng He Bo Li Jinghai Li Xipeng Li Xiaowei Wang Xiaolong Yuan State Key Laboratory o fMulti-Phase Complex System Institute of Process Engineering Chinese Academy of Sciences P.O. Box 353 Beijing 100190 China

A supercomputer with 1.0 Petaflops peak performance in single precision, designed and established by Institute of Process Engineering, Chinese Academy of Sciences, is introduced in this brief communication. A designing philosophy utilizing the similarity between hardware, software and the problems to be solved is embodied, based on the multi-scale method and discrete simulation approaches developed at Institute of Process Engineering （IPE） and implemented in a graphic processing unit （GPU）-based hybrid computing mode. The preliminary applications of this machine in areas of multi-phase flow, molecular dynamics and so on are reported, demonstrating the supercomputer as a paradigm of green computation in new architecture.

关键词： High-performance computing (HPC) Graphic processing unit (GPU) Lattice Boltzmann method Molecular dynamics Multi-phase flow Multi-scale method Particle method

Quasi-real-time simulation of rotating drum using discrete element method with parallel GPU computing

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Particuology 2011年第4期9卷 446-450页

作者： Ji Xu Huabiao Oi Xiaojian Fang Liqiang Lu Wei Ge Xiaowei Wang Ming xu feiguo chen xianfeng He Jinghai Li State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering (IPE) Chinese Academy of Sciences. P.O. Box 353 Beijing 100190 China Graduate University of the Chinese Academy of Sciences Beijing 100039 China

Real-time simulation of industrial equipment is a huge challenge nowadays. The high performance and fine-grained parallel computing provided by graphics processing units （GPUs） bring us closer to our goals. In this article, an industrial-scale rotating drum is simulated using simplified discrete element method （DEM） without consideration of the tangential components of contact force and particle rotation. A single GPU is used first to simulate a small model system with about 8000 particles in real-time, and the simulation is then scaled up to industrial scale using more than 200 GPUs in a 1 D domain-decomposition parallelization mode. The overall speed is about 1/11 of the real-time. Optimization of the communication part of the parallel GPU codes can speed up the simulation further, indicating that such real-time simulations have not only methodological but also industrial implications in the near future.

关键词： Rotating drumReal-time Discrete element method (DEM) Speedup GPU

Quantifying growth and breakage of agglomerates in fluid-particle flow using discrete particle method

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Chinese Journal of Chemical Engineering 2018年第5期26卷 914-921页

作者： Lingfeng Zhou Junwu Wang Wei Ge Shiwen Liu Jianhua chen Ji xu Limin Wang feiguo chen Ning Yang Rongtao Zhou Lin Zhang Qi Chang Philippe Ricoux Alvaro Fernandez State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China Tianjin University Tianjin 300072 China TOTALSA - R&D Groupe Paris 92069 France Total Research & Technology Feluy Belgium Germany

The cohesive solids in liquid flows are featured by the dynamic growth and breakage of agglomerates, and the difficulties in the development, design and optimization of these systems are related to this significant *** this paper, discrete particle method is used to simulate a solid–liquid flow system including millions of cohesive particles, the growth rate and breakage rate of agglomerates are then systematically investigated. It was found that the most probable size of the agglomerates is determined by the balance of growth and breakage of the agglomerates the cross point of the lines of growth rate and breakage rate as a function of the particle numbers in an agglomerate, marks the most stable agglomerate size. The finding here provides a feasible way to quantify the dynamic behaviors of growth and breakage of agglomerates, and therefore offers the possibility of quantifying the effects of agglomerates on the hydrodynamics of fluid flows with cohesive particles.

关键词： Agglomerate Growth and breakage Quantification Discrete particle method