Two relaxation time lattice Boltzmann model for rarefied gas flows

2014 ◽  
Vol 393 ◽  
pp. 51-61 ◽  
Author(s):  
Javad Abolfazli Esfahani ◽  
Ali Norouzi
Keyword(s):  
Relaxation Time ◽  
Lattice Boltzmann ◽  
Rarefied Gas ◽  
Lattice Boltzmann Model ◽  
Gas Flows ◽  
Rarefied Gas Flows ◽  
Boltzmann Model

scholarly journals A Thermal Lattice Boltzmann Model for Micro/Nano-Flows

2008 ◽  
Author(s):  
Y.-H. Zhang ◽  
X.-J. Gu ◽  
R. W. Barber ◽  
D. R. Emerson
Keyword(s):  
Lattice Boltzmann ◽  
Rarefied Gas ◽  
Computational Cost ◽  
Distribution Functions ◽  
Lattice Boltzmann Model ◽  
Gas Flows ◽  
Low Speed ◽  
Rarefied Gas Flows ◽  
Thermal Lattice Boltzmann ◽  
Boltzmann Model

With the development of micro/nano-devices, low speed rarefied gas flows have attracted significant research interest where successful numerical methods for traditional high speed flows, including the direct simulation Monte Carlo method, become computationally too expensive. As the Knudsen number can be up to the order of unity in a micro/nano flow, one approach is to use continuum-based methods including the Navier-Stokes-Fourier (NSF) equations, Burnett/super Burnett equations, and moment models. Limited success has been achieved because of theoretical difficulties and/or numerical problems. The recently developed lattice Boltzmann equation (LBE) offers a fundamentally different approach which is close to kinetic methods but with a significantly smaller computational cost. However, success of LBE methods for rarefied gas motion has been mainly on isothermal flows. In this paper, thermal rarefied gas flows are investigated. Due to the unique features of micro/nano flows, a simplified thermal lattice Boltzmann model with two distribution functions can be used. In addition, kinetic theory boundary conditions for the number density distribution function can be extended to construct a thermal boundary condition. The model has been validated in the slip-flow regime against solutions of the NSF equations for shear and pressure driven flows between two planar plates. It is shown that the present thermal LBE model can capture some unique flow characteristics that the NSF equations fail to predict. The present work indicates that the thermal lattice Boltzmann model is a computationally economic method that is particularly suitable to simulate low speed thermal rarefied gas flows.

Modeling of collapsing cavitation bubble near solid wall by 3D pseudopotential multi-relaxation-time lattice Boltzmann method

2017 ◽  
Vol 232 (3) ◽  
pp. 445-456 ◽  
Author(s):  
Minglei Shan ◽  
Yu Yang ◽  
Hao Peng ◽  
Qingbang Han ◽  
Changping Zhu
Keyword(s):  
Relaxation Time ◽  
Lattice Boltzmann ◽  
Cavitation Bubble ◽  
Solid Wall ◽  
Three Dimensional ◽  
Lattice Boltzmann Model ◽  
Bubble Collapse ◽  
Lattice Boltzmann Simulation ◽  
Boltzmann Method ◽  
Boltzmann Model

Understanding the dynamic characteristic of the cavitation bubble near a solid wall is a fundamental issue for the bubble collapse application and prevention. In the present work, an improved three-dimensional multi-relaxation-time pseudopotential lattice Boltzmann model is adopted to investigate the cavitation bubble collapse near the solid wall. With respect to thermodynamic consistency, Laplace law verification, the three-dimensional pseudopotential multi-relaxation-time lattice Boltzmann model is investigated. By the theoretical analysis, it is proved that the model can be regarded as a solver of the Rayleigh–Plesset equation, and confirmed by comparing the results of the lattice Boltzmann simulation and the Rayleigh–Plesset equation calculation for the case of cavitation bubble collapse in the infinite medium field. The bubble collapse near the solid wall is modeled using the improved pseudopotential multi-relaxation-time lattice Boltzmann model. We find the lattice Boltzmann simulation and the experimental results have the same dynamic process by comparing the bubble profiles evolution. Form the pressure field and the velocity field evolution it is found that the tapered higher pressure region formed near the top of the bubble is a crucial driving force inducing the bubble collapse. This exploratory research demonstrates that the lattice Boltzmann method is an alternative tool for the study of the interaction between collapsing cavitation bubble and matter.

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