Numerical simulation of moving rigid body in rarefied gases

TL;DR

This paper introduces a numerical scheme for simulating the dynamics of a moving rigid body in a rarefied gas, capturing interactions via the Boltzmann equation and validating diffusion coefficients against theoretical values.

Contribution

The paper presents a novel numerical approach combining DSMC and Newton-Euler equations to simulate rigid body motion in rarefied gases, including both translation and rotation.

Findings

Numerical diffusion coefficients match theoretical predictions.

The scheme accurately captures translational and rotational Brownian motion.

Validation confirms the method's effectiveness for complex gas-body interactions.

Abstract

In this paper we present a numerical scheme to simulate a moving rigid body with arbitrary shape suspended in a rarefied gas. The rarefied gas is simulated by solving the Boltzmann equation using a DSMC particle method. The motion of the rigid body is governed by the Newton-Euler equations, where the force and the torque on the rigid body is computed from the momentum transfer of the gas molecules colliding with the body. On the other hand, the motion of the rigid body influences the gas flow in its surroundings. We validate the numerical results by testing the Einstein relation for Brownian motion of the suspended particle. The translational as well as the rotational degrees of freedom are taken into account. It is shown that the numerically computed translational and rotational diffusion coefficients converge to the theoretical values.