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A joint absorbing boundary for the multiple-relaxation-time lattice Boltzmann method in seismic acoustic wavefield modeling 被引量:1
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作者 Chun-Tao Jiang Hui Zhou +2 位作者 Mu-Ming Xia Han-Ming Chen Jin-Xuan Tang 《Petroleum Science》 SCIE EI CAS CSCD 2023年第4期2113-2126,共14页
Conventional seismic wave forward simulation generally uses mathematical means to solve the macroscopic wave equation,and then obtains the corresponding seismic wavefield.Usually,when the subsurface structure is finel... Conventional seismic wave forward simulation generally uses mathematical means to solve the macroscopic wave equation,and then obtains the corresponding seismic wavefield.Usually,when the subsurface structure is finely constructed and the continuity of media is poor,this strategy is difficult to meet the requirements of accurate wavefield calculation.This paper uses the multiple-relaxation-time lattice Boltzmann method(MRT-LBM)to conduct the seismic acoustic wavefield simulation and verify its computational accuracy.To cope with the problem of severe reflections at the truncated boundaries,we analogize the viscous absorbing boundary and perfectly matched layer(PML)absorbing boundary based on the single-relaxation-time lattice Boltzmann(SRT-LB)equation to the MRT-LB equation,and further,propose a joint absorbing boundary through comparative analysis.We give the specific forms of the modified MRT-LB equation loaded with the joint absorbing boundary in the two-dimensional(2D)and three-dimensional(3D)cases,respectively.Then,we verify the effects of this absorbing boundary scheme on a 2D homogeneous model,2D modified British Petroleum(BP)gas-cloud model,and 3D homogeneous model,respectively.The results reveal that by comparing with the viscous absorbing boundary and PML absorbing boundary,the joint absorbing boundary has the best absorption performance,although it is a little bit complicated.Therefore,this joint absorbing boundary better solves the problem of truncated boundary reflections of MRT-LBM in simulating seismic acoustic wavefields,which is pivotal to its wide application in the field of exploration seismology. 展开更多
关键词 multiple-relaxation-time Lattice Boltzmann method Seismic acoustic wavefield simulation Truncated Boundary reflection Joint absorbing boundary
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Cavitation Bubble Collapse near a Curved Wall by the Multiple-Relaxation-Time Shan-Chen Lattice Boltzmann Model 被引量:1
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作者 薛洪惠 单锋 +2 位作者 郭霞生 屠娟 章东 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第8期83-87,共5页
The cavitation bubble collapse near a cell can cause damage to the cell wall. This effect has received increasing attention in biomedical supersonics. Based on the lattice Boltzmann method, a multiple-relaxation-time ... The cavitation bubble collapse near a cell can cause damage to the cell wall. This effect has received increasing attention in biomedical supersonics. Based on the lattice Boltzmann method, a multiple-relaxation-time Shan–Chen model is built to study the cavitation bubble collapse. Using this model, the cavitation phenomena induced by density perturbation are simulated to obtain the coexistence densities at certain temperature and to demonstrate the Young–Laplace equation. Then, the cavitation bubble collapse near a curved rigid wall and the consequent high-speed jet towards the wall are simulated. Moreover, the influences of initial pressure difference and bubble-wall distance on the cavitation bubble collapse are investigated. 展开更多
关键词 Cavitation Bubble Collapse near a Curved Wall by the multiple-relaxation-time Shan-Chen Lattice Boltzmann Model
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Simulations of Bingham plastic flows with the multiple-relaxation-time lattice Boltzmann model 被引量:4
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作者 CHEN SongGui SUN QiCheng +1 位作者 JIN Feng LIU JianGuo 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2014年第3期532-540,共9页
Fresh cement mortar is a type of workable paste, which can be well approximated as a Bingham plastic and whose flow behavior is of major concern in engineering. In this paper, Papanastasiou's model for Bingham fluids... Fresh cement mortar is a type of workable paste, which can be well approximated as a Bingham plastic and whose flow behavior is of major concern in engineering. In this paper, Papanastasiou's model for Bingham fluids is solved by using the multiple- relaxation-time lattice Boltzmann model (MRT-LB). Analysis of the stress growth exponent m in Bingham fluid flow simulations shows that Papanastasiou's model provides a good approximation of realistic Bingham plastics for values of m 〉 108. For lower values of m, Papanastasiou's model is valid for fluids between Bingham and Newtonian fluids. The MRT-LB model is validated by two benchmark problems: 2D steady Poiseuille flows and lid-driven cavity flows. Comparing the numerical results of the velocity distributions with corresponding analytical solutions shows that the MRT-LB model is appropriate for studying Bingham fluids while also providing better numerical stability. We further apply the MRT-LB model to simulate flow through a sudden expansion channel and the flow surrounding a round particle. Besides the rich flow structures obtained in this work, the dynamics fhi d force on the round particle is calculated. Results show that both the Reynolds number Re and the Bingham number Bn affect the drag coefficients Co, and a drag coefficient with Re and Bn being taken into account is proposed. The relationship of Bn and the ratio of unyielded zone thickness to particle diameter is also analyzed. Finally, the Bingham fluid flowing around a set of randomly dispersed particles is simulated to obtain the apparent viscosity and velocity fields. These results help simulation of fresh concrete flowing in porous media. 展开更多
关键词 Bingham fluids multiple-relaxation-time lattice Boltzmann model tbw profiles drag coefficient
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Multiple-relaxation-time lattice Boltzmann model for binary mixtures of nonideal fluids based on the Enskog kinetic theory 被引量:2
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作者 Kang Yang Zhaoli Guo 《Science Bulletin》 SCIE EI CAS CSCD 2015年第6期634-647,M0004,共15页
In this paper, a lattice Boltzmann equation (LBE) model with multiple-relaxation-time (MRT) colli- sion operator is developed based on the Enskog theory for isothermal nonideal mixtures, which is an extension of t... In this paper, a lattice Boltzmann equation (LBE) model with multiple-relaxation-time (MRT) colli- sion operator is developed based on the Enskog theory for isothermal nonideal mixtures, which is an extension of the previous single relaxation time (SRT) LBE model (Guo and Zhao in Phys Rev E 68:035302, 2003). The present MRT-LBE model overcomes some inherent defects of the original SRT-LBE model such as the fixed Schmidt num- ber and limited viscosity ratio. It is also interestingly shown that the widely used Shan-Chen (SC) model, which is constructed heuristically based on the pseudo-potential concept, can also be regarded as a special case of the present model, and thus putting a solid foundation for this well-accepted multiphase LBE model. A series of nu- merical simulations, including the static droplet and lay- ered co-current flow, are conducted to test the applicability of the present model for immiscible fluids with different Schmidt numbers and large viscosity ratio, which may be difficult for the original SRT-LBE model and the SC model. 展开更多
关键词 Lattice Boltzmann equation Enskogequation Bhatnagar-Gross-Krook Singlerelaxation time multiple-relaxation-time
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Two-dimensional Multiple-Relaxation-Time Lattice Boltzmann model for compressible and incompressible flows 被引量:1
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作者 Feng Chen Ai-Guo Xu +1 位作者 Guang-Cai Zhang Yong-Long Wang 《Frontiers of physics》 SCIE CSCD 2014年第2期246-254,共9页
In the paper we extend the Multiple-Relaxation-Time (MRT) Lattice Boltzmann (LB) model pro- posed in [Europhys. Lctt., 2010, 90: 54003] so that it is suitable also for incompressible flows. To decrease tile artif... In the paper we extend the Multiple-Relaxation-Time (MRT) Lattice Boltzmann (LB) model pro- posed in [Europhys. Lctt., 2010, 90: 54003] so that it is suitable also for incompressible flows. To decrease tile artificial oscillations, the convection term is discretized by the flux linfiter scheme with splitting technique. A new model is validated by some well-known benchmark tests, including Rie- mann problem and Couette flow, and satisfying agreements are obtained between the sinmlation results and ana.lytical ones. In order to show the merit of LB model over traditional methods, the non-equilibrium characteristics of system are solved. The simulation results are consistent with the physical analysis. 展开更多
关键词 lattice Boltzmann method multiple-relaxation-time flux limiter technique Prandtlnumbers effect non-equilibrium characteristic
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Improving the Stability of theMultiple-Relaxation-Time Lattice Boltzmann Method by a Viscosity Counteracting Approach 被引量:1
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作者 Chunze Zhang Yongguang Cheng +1 位作者 Shan Huang Jiayang Wu 《Advances in Applied Mathematics and Mechanics》 SCIE 2016年第1期37-51,共15页
Numerical instability may occur when simulating high Reynolds number flows by the lattice Boltzmann method(LBM).The multiple-relaxation-time(MRT)model of the LBM can improve the accuracy and stability,but is still sub... Numerical instability may occur when simulating high Reynolds number flows by the lattice Boltzmann method(LBM).The multiple-relaxation-time(MRT)model of the LBM can improve the accuracy and stability,but is still subject to numerical instability when simulating flows with large single-grid Reynolds number(Reynolds number/grid number).The viscosity counteracting approach proposed recently is a method of enhancing the stability of the LBM.However,its effectiveness was only verified in the single-relaxation-time model of the LBM(SRT-LBM).This paper aims to propose the viscosity counteracting approach for the multiple-relaxationtime model(MRT-LBM)and analyze its numerical characteristics.The verification is conducted by simulating some benchmark cases:the two-dimensional(2D)lid-driven cavity flow,Poiseuille flow,Taylor-Green vortex flow and Couette flow,and threedimensional(3D)rectangular jet.Qualitative and Quantitative comparisons show that the viscosity counteracting approach for the MRT-LBMhas better accuracy and stability than that for the SRT-LBM. 展开更多
关键词 multiple-relaxation-time lattice Boltzmann method viscosity counteracting high Reynolds number flow Poiseuille flow Couette flow Taylor-Green vortex flow lid-driven cavity flow.
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Investigation of mass transfer model of CO_(2) absorption with Rayleigh convection using multi-relaxation time lattice Boltzmann method
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作者 Longyun Zheng Kai Guo +3 位作者 Hongwei Cai Bo Zhang Hui Liu Chunjiang Liu 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2022年第10期130-142,共13页
CO_(2) absorption into absorbents is a widely used method to reduce carbon emissions,in which the concentration gradient near the gas-liquid interface may induce Rayleigh convection(RC).Once RC occurs,the mass transfe... CO_(2) absorption into absorbents is a widely used method to reduce carbon emissions,in which the concentration gradient near the gas-liquid interface may induce Rayleigh convection(RC).Once RC occurs,the mass transfer rate will be significantly enhanced.Therefore,it is necessary to explore the mass transfer enhancement mechanism further and develop a penetration/surface divergence hybrid mass transfer model.In this study,we conduct research on the process of CO_(2) absorption into ethanol with RC.Firstly,we use a multi-relaxation time lattice Boltzmann method to simulate the absorption process and obtain the flow and concentration fields.And we also verify the reliability of the numerical simulation results by comparing with the experimental results.Then,we analyze the characteristics of non-uniform flow and concentration fields in RC.Moreover,we divide the near-interface region into diffusion-dominated and convection-dominated mass transfer zones by checking whether the horizontal average velocity is greater than 1.0×10^(-4) m·s^(-1).Furthermore,based on the differences in mass transfer mechanisms of the aforementioned two zones,we propose a penetration/surface divergence hybrid model to predict the instantaneous mass transfer coefficient.The prediction results demonstrate that the hybrid model can precisely predict the instantaneous mass transfer coefficient of the entire CO_(2) absorption process.Our proposed hybrid model provides a promising way to deal with the complex mass transfer problems with non-uniform flow and concentration fields. 展开更多
关键词 Carbon dioxide ABSORPTION Rayleigh convection Numerical simulation multiple-relaxation-time orgeneralized lattice Boltzmannmodel(MRT-LBM) Mass transfer
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Flux Limiter Lattice Boltzmann for Compressible Flows
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作者 陈峰 许爱国 +1 位作者 张广财 李英骏 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第8期333-338,共6页
In this paper, a new flux limiter scheme with the splitting technique is successfully incorporated into a multiple-relaxation-time lattice Boltzmann (LB) model for shacked compressible flows. The proposed flux limit... In this paper, a new flux limiter scheme with the splitting technique is successfully incorporated into a multiple-relaxation-time lattice Boltzmann (LB) model for shacked compressible flows. The proposed flux limiter scheme is efficient in decreasing the artificial oscillations and numerical diffusion around the interface. Due to the kinetic nature, some interface problems being difficult to handle at the macroscopic level can be modeled more naturally through the LB method. Numerical simulations for the Richtmyer-Meshkov instability show that with the new model the computed interfaces are smoother and more consistent with physical analysis. The growth rates of bubble and spike present a satisfying agreement with the theoretical predictions and other numerical simulations. 展开更多
关键词 lattice Boltzmann method flux limiter technique compressible flows multiple-relaxation-time Richtmyer-Meshkov instability
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Lattice Boltzmann Study of Mixed Convection in a Cubic Cavity
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作者 杜洪艳 柴振华 施保昌 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第7期144-150,共7页
The problem of the mixed convection in a cubic cavity is studied with lattice Boltzmann method. A multiple-relaxation-time lattice Boltzmann model for incompressible flow in the cubic cavity and another thermal lattic... The problem of the mixed convection in a cubic cavity is studied with lattice Boltzmann method. A multiple-relaxation-time lattice Boltzmann model for incompressible flow in the cubic cavity and another thermal lattice Boltzmann model for solving energy/temperature equation are proposed. The present models are first validated through a comparison with some available results, and then, we present a detailed parameter study on the mixed convection in the cubic cavity. The numerical results show that the flow and the Reynolds and Richardson numbers. temperature patterns change greatly with variations of 展开更多
关键词 lattice Boltzmann method multiple-relaxation-time model mixed convection
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Prandtl number effects in MRT lattice Boltzmann models for shocked and unshocked compressible fluids
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作者 Feng Chen,1 Aiguo Xu,2,Guangcai Zhang,2 and Yingjun Li 1,1) State Key Laboratory for GeoMechanics and Deep Underground Engineering,China University of Mining and Technology (Beijing),Beijing 100083,China 2) National Key Laboratory of Computational Physics,Institute of Applied Physics and Computational Mathematics,P.O.Box 8009-26,Beijing 100088,China 《Theoretical & Applied Mechanics Letters》 CAS 2011年第5期60-63,共4页
This paper constructs a new multiple relaxation time lattice Boltzmann model which is not only for the shocked compressible fluids,but also for the unshocked compressible fluids.To make the model work for unshocked co... This paper constructs a new multiple relaxation time lattice Boltzmann model which is not only for the shocked compressible fluids,but also for the unshocked compressible fluids.To make the model work for unshocked compressible fluids,a key step is to modify the collision operators of energy flux so that the viscous coefficient in momentum equation is consistent with that in energy equation even in the unshocked system.The unnecessity of the modification for systems under strong shock is analyzed.The model is validated by some well-known benchmark tests,including thermal Couette flow,Riemann problem.The first system is unshocked and the latter is shocked.In both systems,the Prandtl number effects are checked.Satisfying agreements are obtained between new model results and analytical ones. 展开更多
关键词 lattice Boltzmann method compressible flows multiple-relaxation-time Prandtl number
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Viscosity, heat conductivity, and Prandtl number effects in the Rayleigh-Taylor Instability 被引量:10
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作者 Feng Chen Ai-Guo Xu Guang-Cai Zhang 《Frontiers of physics》 SCIE CSCD 2016年第6期183-196,共14页
The two-dimensional Rayleigh-Taylor instability problem is simulated with a multiple-relaxation-time discrete Boltzmann model with a gravity term. Viscosity, heat conductivity, and Prandtl number effects are probed fr... The two-dimensional Rayleigh-Taylor instability problem is simulated with a multiple-relaxation-time discrete Boltzmann model with a gravity term. Viscosity, heat conductivity, and Prandtl number effects are probed from macroscopic and nonequilibrium viewpoints. In the macro sense, both viscosity and heat conduction show a significant inhibitory effect in the reacceleration stage, which is mainly achieved by inhibiting the development of the Kelvin-Helmholtz instability. Before this, the Prandtl number effect is not sensitive. Viscosity, heat conductivity, and Prandtl number effects on nonequilibrium manifestations and the degree of correlation between the nonuniformity and the nonequilibrium strength in the complex flow are systematically investigated. 展开更多
关键词 discrete Boltzmann model/method multiple-relaxation-time Rayleigh-Taylor instability NONEQUILIBRIUM
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Entropy Generation Analysis around Airfoil using Multi-Block Lattice Boltzmann Method
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作者 Wei Wang Jun Wang +1 位作者 Zhiang Li Zhiliang Lin 《Advances in Applied Mathematics and Mechanics》 SCIE 2022年第3期777-798,共22页
This present paper proposes aerodynamic forces and entropy generation characteristics on theflow past two-dimensional airfoil at low Reynolds number by multiple-relaxation-time lattice Boltzmann method to clarify theflo... This present paper proposes aerodynamic forces and entropy generation characteristics on theflow past two-dimensional airfoil at low Reynolds number by multiple-relaxation-time lattice Boltzmann method to clarify theflow loss mechanism.The block mesh refinement was adopted in which a higher accuracy was needed in parts of the domain characterized by complexflow.The interpolated bounce-back method was used to treat the irregular curve.This numerical method can effectively solve the complexflowfield simulation problems with reasonable accuracy and reli-ability by simulatingflow around plate and airfoil.Based on second law of thermo-dynamics,an expression of entropy generation rate for arbitrary control volume was derived theoretically which could accurately quantify the local irreversible loss of theflowfield at any position.After that,a comprehensive numerical study was conducted to analyze relationship of entropy generation and drag force by taking NACA0012 air-foil as the research object.For unsteady condition,entropy generation rate and the drag force are not linearly related any more.Losses due to steady effects mainly con-sider the irreversibility in the boundary layer and wake while the unsteady effects come from the interaction between the main separation vortex and the trailing shed-ding vortex. 展开更多
关键词 Loss mechanism entropy generation flow past airfoil lattice Boltzmann method multiple-relaxation-time block mesh refinement
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