DSMC-LBM mapping scheme for rarefied and non-rarefied gas flows

TL;DR

This paper introduces a kinetic mapping scheme between DSMC and LBM to efficiently simulate flows with variable rarefaction, enabling accurate coupling at higher Kn numbers and improving computational efficiency.

Contribution

The paper presents a novel kinetic mapping scheme that enhances hybrid DSMC-LBM coupling for rarefied gas flows, allowing accurate simulations at higher Knudsen numbers.

Findings

Good agreement between mapped moments and independent simulations

Effective coupling at larger Kn numbers than traditional methods

Potential computational efficiency gains

Abstract

We present the formulation of a kinetic mapping scheme between the Direct Simulation Monte Carlo (DSMC) and the Lattice Boltzmann Method (LBM) which is at the basis of the hybrid model used to couple the two methods in view of efficiently and accurately simulate isothermal flows characterized by variable rarefaction effects. Owing to the kinetic nature of the LBM, the procedure we propose ensures to accurately couple DSMC and LBM at a larger Kn number than usually done in traditional hybrid DSMC-Navier-Stokes equation models. We show the main steps of the mapping algorithm and illustrate details of the implementation. Good agreement is found between the moments of the single particle distribution function as obtained from the mapping scheme and from independent LBM or DSMC simulations at the grid nodes where the coupling is imposed. We also show results on the application of the hybrid scheme based on a simpler mapping scheme for plane Poiseuille flow at finite Kn number. Potential gains in the computational efficiency assured by the application of the coupling scheme are estimated for the same flow.