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Rare Metals 2020年第2期39卷 147-155页

作者： Cong Yang Qing-Yan Xu Bai-Cheng Liu Key Laboratory for Advanced Materials Processing Technology(Ministry of Education) School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

The thermosolutal convection can alter segregation pattern,change dendrite morphology and even cause freckles formation in alloy *** this work,the multiphase-field model was coupled with lattice boltzmann method to simulate the dendrite growth under melt convection in superalloy *** the isothermal solidification simulations,zero and normal gravitational accelerations were applied to investigate the effects of gravity on the dendrite morphology and the magnitude of melt *** solute distribution of each alloy component along with the dendrite tip velocity during solidification was obtained,and the natural convection has been confirmed to affect the microsegregation pattern and the dendrite growth *** the directional solidification simulations,two typical temperature gradients were applied,and the dendrite morphology and fluid velocity in the mushy zone during solidification were *** is found that the freckles will form when the average fluid velocity in the mushy zone exceeds the withdraw velocity.

关键词： Dendrite growth Natural convection Phasefield model Lattice boltzmann method

Numerical simulation of dam break flow impact on vertical cylinder by cumulant lattice boltzmann method

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Journal of Hydrodynamics 2021年第2期33卷 185-194页

作者： Seiya Watanabe Shintaro Fujisaki Changhong Hu Research Institute for Applied Mechanics Kyushu UniversityFukuokaJapan School of Engineering Sciences Kyushu UniversityFukuokaJapan

The purpose of this study is to apply the cumulant lattice boltzmann method(LBM)to simulate high Reynolds number free surface *** single-phase cumulant LBM is extended to solve the free surface flows by using the phase-field method as the interface capturing *** simulations are performed on an experimental problem of dam break flow impact on a vertical *** numerical aspects such as collision model,grid resolution,time step and interface mobility parameter are *** is found that the severe impact pressure oscillation in the simulation by the conventional SRT model,can be significantly suppressed by the cumulant *** agreement between the cumulant LBM numerical simulation and the experiment has been obtained on both the free surface profiles and the impact *** numerical results obtained by the present study demonstrate that the cumulant LBM can be a powerful numerical tool for simulations of violent free surface flow problems.

关键词： Lattice boltzmann method(LBM) free surface flow wave impact pressure dam break flow cumulant model

Lattice boltzmann Simulation of a Gas-to-Solid Reaction and Precipitation Process in a Circular Tube

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Computer Modeling in Engineering & Sciences 2018年第12期117卷 527-553页

作者： Matthew D.Lindemer Suresh G.Advani Ajay K.Prasad Department of Mechanical and Industrial Engineering University of Minnesota Duluth1049 University DriveDuluthMN 55812USA Department of Mechanical Engineering University of DelawareNewarkDE 19716USA.

The lattice boltzmann method(LBM)is used to simulate the growth of a solid-deposit on the walls of a circular tube resulting from a gas-to-solid reaction and precipitation *** process is of particular interest for the design of reactors for the production of hydrogen by the heterogeneous hydrolysis of steam with Zn vapor in the Zn/ZnO thermochemical *** solid deposit of ZnO product on the tube wall evolves in time according to the temporally-and axially-varying convective-diffusive transport and reaction of Zn vapor with steam on the solid *** LBM is wellsuited to solving problems with coupled flow,heat and mass transfer in a time-evolving ***,a D2Q9 axisymmetric multiple-relaxation-time(MRT)lattice boltzmann scheme is used to simulate incompressible fluid transport while a D2Q5 axisymmetric MRT lattice boltzmann scheme is used to simulate the convective-diffusive transport of Zn *** model is first validated against several analytical solutions,followed by a parametric study to understand the effect of Reynolds,Schmidt,and Damk?hler numbers on the time evolution of the ZnO deposition profile along the tube *** axial location of the fastest deposition is found to increase with increasing Peclet number,and decrease with increasing Damk?hler number,with no independent effect from the Schmidt *** the reaction kinetics are assumed to increase along the tube axis due to nonisothermal tube wall temperature,a second peak in the deposition profile can be observed for sufficiently low values of Da/Pe.

关键词： Lattice boltzmann methods reactive flow heterogeneous reaction precipitation solar hydrogen production.

A numerical study for WENO scheme-based on different lattice boltzmann flux solver for compressible flows

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Acta Mechanica Sinica 2018年第6期34卷 995-1014页

作者： You Li Xiao-Dong Niu Hai-Zhuan Yuan Adnan Khan Xiang Li College of Engineering Shantou UniversityShantou 515063China School of Mathematics and Computational Science Xiangtan UniversityXiangtan 411105China

In this paper,the finite difference weighted essentially non-oscillatory (WENO) scheme is incorporated into the recently developed four kinds of lattice boltzmann flux solver (LBFS) to simulate compressible flows,including inviscid LBFS Ⅰ,viscous LBFS Ⅱ,hybrid LBFS Ⅲ and hybrid LBFS Ⅳ.Hybrid LBFS can automatically realize the switch between inviscid LBFS Ⅰ and viscous LBFS Ⅱ through introducing a switch *** resultant hybrid WENO-LBFS scheme absorbs the advantages of WENO scheme and hybrid *** investigate the performance of WENO scheme based on four kinds of LBFS *** results indicate that the devopled hybrid WENO-LBFS scheme has high accuracy,high resolution and no *** can not only accurately calculate smooth solutions,but also can effectively capture contact discontinuities and strong shock waves.

关键词： WENO scheme Hybrid Lattice boltzmann flux solver Compressible inviscid flows Contact discontinuities Shock waves

A numerical study on pattern selection in crystal growth by using anisotropic lattice boltzmann-phase field method

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Chinese Physics B 2020年第2期29卷 446-457页

作者： Zhaodong Zhang Yuting Cao Dongke Sun Hui Xing Jincheng Wang Zhonghua Ni School of Mechanical Engineering Southeast UniversityNanjing 211189China MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Shaanxi Key Laboratory for Condensed Matter Structure and PropertiesNorthwestern Polytechnical University(NPU)Xi'an 710129China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China

Pattern selection during crystal growth is studied by using the anisotropic lattice boltzmann-phase field *** the model,the phase transition,melt flows,and heat transfer are coupled and mathematically described by using the lattice boltzmann(LB)*** anisotropic streaming-relaxation operation fitting into the LB framework is implemented to model interface advancing with various preferred *** pattern evolutions are then numerically investigated in the conditions of with and without melt *** is found that melt flows can significantly influence heat transfer,crystal growth behavior,and phase *** crystal morphological transition from dendrite,seaweed to cauliflower-like patterns occurs with the increase of *** interface normal angles and curvature distributions are proposed to quantitatively characterize crystal *** results demonstrate that the distributions are corresponding to crystal morphological features,and they can be therefore used to describe the evolution of crystal patterns in a quantitative way.

关键词： lattice boltzmann crystal growth phase field melt flow pattern selection

An Improved Enthalpy-Based Lattice boltzmann 3D Model with Added Probability Function for the Growth Characteristics of Frost Layer

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Journal of Thermal Science 2019年第2期28卷 378-392页

作者： CUI Jing YANG Tinghao YANG Fan YANG Guangfeng Airport College Civil Aviation University of China

In this paper, the effects of different surface properties on the growth of frost layer were numerically studied from the mesoscopic scale using the lattice boltzmann method. The improved enthalpy method and nucleation probability model were combined to establish a three-dimensional lattice boltzmann model based on nucleation probability theory. The model was used to carry out numerical research on frost layer formation and growth process on cold wall surface. The model could not only simulate the gradual densification and thickening process of frost layer growth from the macro scale, but also describe the change process of the frost layer structure caused by ice branch growth on the micro scale. The average thickness, average density and the amount of the frost layer could be obtained. Through this model, the temporal and spatial evolution characteristics of the topography of the frost layer were obtained. The model was used to analyze the effects of cold wall surface temperature, relative humidity and cold surface wettability on the frosting characteristics. The average thickness, frost average density, frost quality and average solid volume fraction of frost at different times were obtained by calculation.

关键词： lattice boltzmann model improved enthalpy model nucleation probability model three-dimensional frost surface wettability

Study on the unified algorithm for three-dimensional complex problems covering various flow regimes using boltzmann model equation

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Science China(Physics,Mechanics & Astronomy) 2009年第1期52卷 124-138页

作者： LI ZhiHui1,2 & ZHANG HanXin1 1 National Laboratory for Computational Fluid Dynamics, Beijing 100083, China 2 China Aerodynamics Research and Development Center, Hypervelocity Aerodynamics Institute, Mianyang 621000, China National Laboratory for Computational Fluid Dynamics Beijing China China Aerodynamics Research and Development Center Hypervelocity Aerodynamics Institute Mianyang China

The boltzmann simplified velocity distribution function equation describing the gas transfer phenomena from various flow regimes will be explored and solved numerically in this study. The discrete velocity ordinate method of the gas kinetic theory is studied and applied to simulate the complex multi-scale flows. Based on the uncoupling technique on molecular movement and colliding in the DSMC method, the gas-kinetic finite difference scheme is constructed to directly solve the discrete velocity distribution functions by extending and applying the unsteady time-splitting method from computational fluid dynamics. The Gauss-type discrete velocity numerical quadrature technique for different Mach number flows is developed to evaluate the macroscopic flow parameters in the physical space. As a result, the gas-kinetic numerical algorithm is established to study the three-dimensional complex flows from rarefied transition to continuum regimes. The parallel strategy adapted to the gas-kinetic numerical algorithm is investigated by analyzing the inner parallel degree of the algorithm, and then the HPF parallel processing program is developed. To test the reliability of the present gas-kinetic numerical method, the three-dimensional complex flows around sphere and spacecraft shape with various Knudsen numbers are simulated by HPF parallel computing. The computational results are found in high resolution of the flow fields and good agreement with the theoretical and experimental data. The computing practice has confirmed that the present gas-kinetic algorithm probably provides a promising approach to resolve the hypersonic aerothermodynamic problems with the complete spectrum of flow regimes from the gas-kinetic point of view of solving the boltzmann model equation.

关键词： boltzmann model equation kinetic theory velocity distribution function discrete velocity ordinate technique hypersonic flow parallel computing numerical methods

Lattice boltzmann method for simulation of time-dependent neutral particle transport

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Nuclear Science and Techniques 2017年第3期28卷 74-84页

作者： Ya-Hui Wang Li-Ming Yan Bang-Yang Xia Yu Ma School of Energy Science and Engineering Harbin Institute of Technology Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China

In this paper, a novel model is proposed to investigate the neutron transport in scattering and absorbing medium. This solution to the linear boltzmann equation is expanded from the idea of lattice boltzmann method(LBM) with the collision and streaming process. The theoretical derivation of lattice boltzmann model for transient neutron transport problem is proposed for the first *** fully implicit backward difference scheme is used to ensure the numerical stability, and relaxation time and equilibrium particle distribution function are obtained. To validate the new lattice boltzmann model, the LBM formulation is tested for a homogenous media with different sources, and both transient and steady-state LBM results get a good agreement with the benchmark solutions.

关键词： Transient neutron transport Lattice boltzmann method Linear boltzmann equation

A mass-conserved multiphase lattice boltzmann method based on high-order difference

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Chinese Physics B 2020年第3期29卷 292-302页

作者： Zhang-Rong Qin Yan-Yan Chen Feng-Ru Ling Ling-Juan Meng Chao-Ying Zhang Guangxi Collaborative Innovation Center of Multi-source Information Integration and Intelligent Processing Guangxi Normal UniversityGuilin 541004China

The Z–S–C multiphase lattice boltzmann model [Zheng, Shu, and Chew(ZSC), J. Comput. Phys. 218, 353(2006)]is favored due to its good stability, high efficiency, and large density ratio. However, in terms of mass conservation, this model is not satisfactory during the simulation computations. In this paper, a mass correction is introduced into the ZSC model to make up the mass leakage, while a high-order difference is used to calculate the gradient of the order parameter to improve the accuracy. To verify the improved model, several three-dimensional multiphase flow simulations are carried out,including a bubble in a stationary flow, the merging of two bubbles, and the bubble rising under buoyancy. The numerical simulations show that the results from the present model are in good agreement with those from previous experiments and simulations. The present model not only retains the good properties of the original ZSC model, but also achieves the mass conservation and higher accuracy.

关键词： lattice boltzmann method high-order difference mass conservation large density ratio

Boundary scheme for lattice boltzmann modeling of micro-scale gas flow in organic-rich pores considering surface diffusion

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Chinese Physics B 2019年第3期28卷 84-96页

作者： Hong Zuo Shou-Chun Deng Hai-Bo Li State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China

We propose a boundary scheme for addressing multi-mechanism flow in a porous medium in slip and early transition flow regimes, which is frequently encountered in shale gas reservoirs. Micro-gaseous flow in organic-rich shale involves a complex flow mechanism. A self-developed boundary scheme that combines the non-equilibrium extrapolation scheme and the combined diffusive reflection and bounce-back scheme(half-way DBB) to embed the Langmuir slip boundary into the single-relaxation-time lattice boltzmann method(SRT-LBM) enables us to describe this process, namely, the coupling effect of micro-gaseous flow and surface diffusion in organic-rich nanoscale pores. The present LBM model comes with the careful consideration of the local Knudsen number, local pressure gradient, viscosity correction model, and regularization procedure to account for the rarefied gas flows in irregular pores. Its validity and accuracy are verified by several benchmarking cases, and the calculated results by this boundary scheme accord well with our analytical *** boundary scheme shows a higher accuracy than the existing studies. Additionally, a subiteration strategy is presented to tackle the coupled micro-gaseous flow and surface diffusion, which necessitates the iteration process matching of these two mechanisms. The multi-mechanism flow in the self-developed irregular pores is also numerically investigated and analyzed over a wide range of parameters. The results indicate that the present model can effectively capture the coupling effect of micro-gaseous flow and surface diffusion in a tree-like porous medium.

关键词： lattice boltzmann method(LBM) surface diffusion Langmuir slip model boundary scheme