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Accelerating fully resolved simulation of particle-laden flows on heterogeneous computer architectures

Particuology 2023年第10期81卷 25-37页

作者： Kuang Ma maoqiang jiang Zhaohui Liu State Key Laboratory of Coal Combustion School of Energy and Power EngineeringHuazhong University of Science and TechnologyWuhan430074China Department of Mechanical Engineering National University of Singapore117575Singapore

An efficient computing framework,namely PFlows,for fully resolved-direct numerical simulations of particle-laden flows was accelerated on NVIDIA General Processing Units(GPUs)and GPU-like accelerator(DCU)cards.The framework is featured as coupling the lattice Boltzmann method for fluid flow with the immersed boundary method for fluid-particle interaction,and the discrete element method for particle collision,using two fixed Eulerian meshes and one moved Lagrangian point mesh,respectively.All the parts are accelerated by a fine-grained parallelism technique using CUDA on GPUs,and further using HIP on DCU cards,i.e.,the calculation on each fluid grid,each immersed boundary point,each particle motion,and each pair-particle collision is responsible by one computer thread,respectively.Coalesced memory accesses to LBM distribution functions with the data layout of Structure of Arrays are used to maximize utilization of hardware bandwidth.Parallel reduction with shared memory for data of immersed boundary points is adopted for the sake of reducing access to global memory when integrate particle hydrodynamic force.MPI computing is further used for computing on heterogeneous architectures with multiple CPUs-GPUs/DCUs.The communications between adjacent processors are hidden by overlapping with calculations.Two benchmark cases were conducted for code validation,including a pure fluid flow and a particle-laden flow.The performances on a single accelerator show that a GPU V100 can achieve 7.1–11.1 times speed up,while a single DCU can achieve 5.6–8.8 times speed up compared to a single Xeon CPU chip(32 cores).The performances on multi-accelerators show that parallel efficiency is 0.5–0.8 for weak scaling and 0.68–0.9 for strong scaling on up to 64 DCU cards even for the dense flow(φ=20%).The peak performance reaches 179 giga lattice updates per second(GLUPS)on 256 DCU cards by using 1 billion grids and 1 million particles.At last,a large-scale simulation of a gas-solid flow with 1.6 billion grids and 1.6 million particles wa

关键词： Lattice Boltzmann method Immersed boundary method Particle-ladenflows Heterogeneous acceleration General Processing Units

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Fully resolved simulations of viscoelastic suspensions by an efficient immersed boundary-lattice Boltzmann method

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Particuology 2023年第4期75卷 26-49页

作者： Shenxu Qin maoqiang jiang Kuang Ma Jin Su Zhaohui Liu State Key Laboratory of Coal Combustion School of Energy and Power EngineeringHuazhong University of Science and TechnologyWuhan430074China School of Science Xian Polytechnic UniversityXi'an710048China

An efficient immersed boundary-lattice Boltzmann method(IB-LBM)is proposed for fully resolved simulations of suspended solid particles in viscoelastic flows.Stress LBM based on Giesekus and Oldroyd-B constitutive equation are used to model the viscoelastic stress tensor.A boundary thickening-based direct forcing IB method is adopted to solve the particle-fluid interactions with high accuracy for non-slip boundary conditions.A universal law is proposed to determine the diffusivity constant in a viscoelastic LBM model to balance the numerical accuracy and stability over a wide range of computa-tional parameters.An asynchronous calculation strategy is adopted to further improve the computing efficiency.The method was firstly applicated to the simulation of sedimentation of a single particle and a pair of particles after good validations in cases of the flow past a fixed cylinder and particle migration in a Couette flow against FEM and FVM methods.The determination of the asynchronous calculation strategy and the effect of viscoelastic stress distribution on the settling behaviors of one and two particles are revealed.Subsequently,504 particles settling in a closed cavity was simulated and the phenomenon that the viscoelastic stress stabilizing the Rayleigh-Taylor instabilities was observed.At last,simulations of a dense flow involving 11001 particles,the largest number of particles to date,were performed to investigate the instability behavior induced by elastic effect under hydrodynamic interactions in a viscoelastic fluid.The elasticity-induced ordering of the particle structures and fluid bubble structures in this dense flow is revealed for the first time.These simulations demonstrate the capability and prospects of the present method for aid in understanding the complex behaviors of viscoelastic particle suspensions.

关键词： Fullyresolved simulation Lattice Boltzmann method Immersed boundary method Viscoelastic suspension Particle sedimentation

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Inertial migration of aerosol particles in three-dimensional microfluidic channels

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Particuology 2021年第2期19卷 23-34页

作者： Shizhi Qian maoqiang jiang Zhaohui Liu Department of Mechanical and Aerospace Engineering Old Dominion UniversityNorfolkVA 23529USA State Key Laboratory of Coal Combustion School of Energy and Power EngineeringHuazhong University of Science and TechnologyWuhan 430074China Smith School of Chemical and Biomolecular Engineering Cornell UniversityIthaca NY 14853USA

In recent years,manipulation of particles by inertial microfluidics has attracted significant attention.However,most studies focused on inertial focusing of particles suspended within liquid phase,in which the ratio of the density of the particle to that of the medium is O(1).The investigation on manipulation of aerosol particles in an inertial microfluidics is very limited.In this study,we numerically investigate the aerosol particle's motion in a 3D straight microchannel with rectangular cross section by fully resolved simulation of the particle-air flow.The air flow is modeled by the Navier-Stokes equations.The particle's motions,including translation and rotation,are governed,respectively,by the Newton's second law and the Euler equations without using any approximation models for the lift and drag forces.The coupled mathematical model is numerically solved by combining immersed boundary with lattice Boltzmann method(IB-LBM).We find that the Reynolds number(Re),the particle's initial position,particle's density and diameter are the influential parameters in this process.The equilibrium positions and their stabilities of aerosols are different from those suspended in liquid.

关键词： Fully resolved simulation Bioaerosol Lattice Boltzmann method Immersed boundary method

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Particle-scale simulation of fluidized bed with immersed tubes

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Frontiers of Chemical Science and Engineering 2008年第3期2卷 341-345页

作者： Yongzhi ZHAO maoqiang jiang Yi CHENG Department of Chemical and Biochemical Engineering Zhejiang UniversityHangzhou 310027China Department of Chemical Engineering Tsinghua UniversityBeijing 100084China

In order to simulate gas-solids flows with complex geometry,the boundary element method was incorporated into the implementation of a combined model of computational fluid dynamics and discrete element method.The resulting method was employed to simulate hydrodynamics in a fluidized bed with immersed tubes.The transient simulation results showed particle and bubble dynamics.The bubble coalescence and break-up behavior when passing the immersed tubes was successfully predicted.The gassolid flow pattern in the fluidized bed is changed greatly because of the immersed tubes.As particles and gas are come in contact with the immersed tubes,the gas bubbles will be deformed.The collisions between particles and tubes will make the tubes surrounded by air pockets most of the time and this is unfavorable for the heat transfer between particles and tubes.

关键词： computational fluid dynamics discrete element method boundary element method fluidized bed

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Numerical simulation of two-dimensional spouted bed with draft plates by discrete element method

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Frontiers of Chemical Science and Engineering 2008年第1期2卷 5-9页

作者： Yongzhi ZHAO Yi CHENG maoqiang jiang Yong JIN Department of Chemical and Biochemical Engineering Zhejiang UniversityHangzhou 310027China Beijing Key Laboratory of Green Reaction Engineering and Technology Department of Chemical EngineeringTsinghua UniversityBeijing 100084China

A discrete element method(DEM)-computa-tional fluid dynamics(CFD)two-way coupling method was employed to simulate the hydrodynamics in a two-dimensional spouted bed with draft plates.The motion of particles was modeled by the DEM and the gas flow was modeled by the Navier-Stokes equation.The interactions between gas and particles were considered using a two-way coupling method.The motion of particles in the spouted bed with complex geometry was solved by com-bining DEM and boundary element method(BEM).The minimal spouted velocity was obtained by the BEM-DEM-CFD simulation and the variation of the flow pat-tern in the bed with different superficial gas velocity was studied.The relationship between the pressure drop of the spouted bed and the superficial gas velocity was achieved from the simulations.The radial profile of the averaged vertical velocities of particles and the profile of the aver-aged void fraction in the spout and the annulus were stat-istically analyzed.The flow characteristics of the gas-solid system in the two-dimensional spouted bed were clearly described by the simulation results.

关键词： discreteelement method computational fluid dynamics spouted bed boundary element method

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考虑信息不对称的综合能源系统运营商鲁棒定价策略

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南方电网技术 2024年第1期18卷 102-110,133页

作者：陈曦彭泓华刘一钟林健怡江天炎毕茂强重庆理工大学电气与电子工程学院重庆400054 重庆市能源互联网工程技术研究中心重庆400054 重庆大学经济与工商管理学院重庆400044

随着新型电力系统的建设要求和市场化的逐步推进,综合能源系统运营商(integrated energy operator,IEO)需要制定合理的价格策略向能源用户(energy user,EU)供能并获取运营收益。为了揭示信息不对称及其程度对IEO定价行为策略演化的影响... 详细信息

随着新型电力系统的建设要求和市场化的逐步推进,综合能源系统运营商(integrated energy operator,IEO)需要制定合理的价格策略向能源用户(energy user,EU)供能并获取运营收益。为了揭示信息不对称及其程度对IEO定价行为策略演化的影响规律,构建了以IEO为定价决策主导者、EU负荷调整为跟随者的Stackelberg主从博弈定价模型,引入信息间隙决策理论和鲁棒博弈方法来刻画并求解信息不对称度对IEO-EU定价博弈行为的影响。结合实际算例分析了信息不对称度对IEO定价收益和EU收益的影响,研究了信息不对称度与IEO最优定价的定量关系,提出了考虑信息不对称度的IEO鲁棒定价策略。算例分析表明在信息不对称的情况下IEO可以利用信息优势谋取过高定价,超额利润随信息不对称程度的增加而增大。政府监管部门应提高对IEO的信息公开和信息披露要求,提升EU对能源价格和能源成本的认知。

关键词：信息不对称园区综合能源系统定价策略鲁棒博弈信息间隙决策理论

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Wavelet method optimised by ant colony algorithm used for extracting stable and unstable signals in intelligent substations

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CAAI Transactions on Intelligence Technology 2022年第2期7卷 292-300页

作者： Tianyan jiang Xiao Yang Yuan Yang Xi Chen maoqiang Bi Jianfei Chen School of Electrical and Electronic Engineering Chongqing University of TechnologyChongqingChina DepartmentState Key Laboratory of Power Transmission Equipment&System and New Technology Chongqing UniversityChongqingChina Department of Electrical and Computer Engineering University of MarylandCollege ParkMarylandUSA

Partial discharge(PD)signals are an important index to evaluate the operation state of intelligent substations.The correct distinction of PD pulse and interference pulse has become a challenging task.Because of the noise and the low signal-to-noise ratio,the stable signals become non-stationary.The selection of a wavelet basis,the selection rule of thresholdλand the design of the threshold function are the key factors affecting the final denoising effect.Therefore,an enhanced ant colony optimisition wavelet(ACOW)algorithm was applied to find the global optimal threshold through the continuous derivative threshold function and the ant colony optimisation(ACO)algo-rithm.At the same time the efficiency of adaptive search calculation,was also significantly improved.The method of the ACOW algorithm was compared with the soft wavelet method,gradient-based wavelet method and the genetic optimisation wavelet(GOW)method.Using these four methods to denoise four typical signals,different mean square errors(MSE),magnitude errors(ME)and time costs were obtained.Interestingly,the results show that the ACOW method can achieve the minimum MSE and has less time cost.It generates significantly smaller waveform distortion than the other three threshold estimation methods.In addition,the high efficiency and good quality of the output signals are beneficial to the diagnosis of local discharge signals in intelligent substations.

关键词： algorithm noise method

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Feature extraction of partial discharge in low-temperature composite insulation based on VMD-MSE-IF

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CAAI Transactions on Intelligence Technology 2022年第2期7卷 301-312页

作者： Xi Chen Xiao Shao Xin Pan Gaochao Luo maoqiang Bi Tianyan jiang Kang Wei School of Electrical and Electronic Engineering Chongqing University of TechnologyChongqingChina Chongqing Wanzhou District Municipal Facilities Maintenance and Management Center ChongqingChina Meta Platforms Inc Menlo ParkCaliforniaUSA

Low-temperature composite insulation is commonly applied in high-temperature super-conducting apparatus while partial discharge(PD)is found to be an important indicator to reveal insulation statues.In order to extract feature parameters of PD signals more effectively,a method combined variational mode decomposition with multi-scale entropy and image feature is proposed.Based on the simulated test platform,original and noisy signals of three typical PD defects were obtained and decomposed.Accordingly,relative moments and grayscale co-occurrence matrix were employed for feature extraction by K-modal component diagram.Afterwards,new PD feature vectors were obtained by dimension reduction.Finally,effectiveness of different feature extraction methods was evaluated by pattern recognition based on support vector machine and K-nearest neighbour.Result shows that the proposed feature extraction method has a higher recognition rate by comparison and is robust in processing noisy signals.

关键词： feature extraction pattern recognition

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Novel dc flashover model for predicting flashover voltage of the iced insulators

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High Voltage 2021年第1期6卷 149-159页

作者： Caijin Fan Xingliang jiang Yanbin Xie Jianlin Hu Zhijin Zhang Qin Hu maoqiang Bi State Key Laboratory of Power Transmission Equipment and System Security and New Technology College of Electrical EngineeringChongqing UniversityShapingba District ChongqingChina Electric Power Research Institute CSGGuangzhouChina School of Electrical Engineering Shaoyang UniversityHunanChina School of Electrical and Electronic Engineering Chongqing University of TechnologyChongqingChina

This work first proposes a novel flashover model based on the deduced residual resis-tance of the ice layer. The most important finding of the field icing tests is that the double‐layer ice‐melting water film exists on the inner and outer surfaces of the ice layer. The conductivity of melting water on the inner and outer surface of the ice layer has been measured, and the corresponding surface conductivity has been calculated. According to the proposed flashover model, the ratio η of the resistance of the ice layer to that of the pollution layer gradually increases with the increase of the ratio k of the resistance of the outer surfaces to that of inner surfaces, and eventually approaches saturation. Further-more, the icing flashover criterion has been modified, and the voltage gradient of the inner surface is less than that of the outer surface. Test results show that the ice flashover voltage is lower than the pollution flashover voltage between 2.18-9.69% and 14.75- 20.32% under light ice and semi‐cylindrical ice, respectively. The simulation results based on the proposed model and the classic model are compared with the field test data. Results show that the proposed model could attain a high accuracy of dc flashover voltage and demonstrate the effectiveness of the proposed model.

关键词： flash outer conductivity

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Enhancing mixing of particles by baffies in a rotating drum mixer

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Particuology 2011年第3期9卷 270-278页

作者： maoqiang jiang Yongzhi Zhao Gesi Liu Jinyang Zheng State Key Laboratory of Chemical Engineering Institute of Chemical Process Equipment Department of Chemical and Biochemical Engineering Zhejiang University Hangzhou 310027China

Baffles with shape of ＂-＂（single baffle）, ＂＋＂（cross-baffles with four arms） and （baffles with 6 arms） are used to enhance the mixing of particles in a rotating drum mixer. A micro-dynamics study of mixing and segregation ofa bi-disperse system of two particle sizes in the rotating drum with these three kinds of baffles is carried out using the discrete element method （DEM）. The effect of the baffles on mixing, and the mechanisms of mixing enhancement by the baffles are discussed and analyzed. Simulation results show that in an unbaffled drum mixer, particle convection, particle diffusion, and size segregation of hi- disperse particles, all play important roles in the mixing process; whereas size segregation will be largely restrained when the drum mixer has a baffle, regardless of its shape, and the degree of mixing is higher than that in an unbaffled drum mixer. The different mixing characteristics for ＂-＂ shaped baffle, ＂＋＂ baffle, and baffle are revealed by the simulation results. For ＂＋＂ or style baffles, there is an optimal size of baffles for the mixing of particles, and the ootimal mixing efficiency is higher than that for ＂-＂ baffle.

关键词： Particle mixing Size segregation Baffle Drum mixer Discrete element method （DEM）

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