Meshes are commonly used as part of instruments for in situ atmospheric measurements. This study analyses the aerodynamic effect of meshes by means of wind tunnel experiments and numerical simulations. Based on the Direct Simulation Monte Carlo method, a simple mesh parameterisation is described and applied to a number of representative flow conditions. For open meshes freely exposed to the flo...

Rarefied gas flows through micro-channels are simulated using particle approaches, named as the information preservation (IP) method and the direct simulation Monte Carlo (DSMC) method. In simulating the low speed flows in long micro-channels the DSMC method encounters the problem of large sample size demand and the difficulty of regulating boundary conditions at the inlet and outlet. Some impo...

Sound propagation through a rarefied gas inside a two-dimensional cavity is investigated on the basis of the linearized Boltzmann equation, where one of the cavity walls oscillates harmonically in the direction normal to its own surface and is considered as a sound source. An analytical solution at high oscillation frequencies is obtained and detailed numerical results for a wide range of gas r...

In this paper, we use a lattice Boltzmann model (LBM) for simulation of rarefied gas flows in microchannels at high and moderate Knudsen numbers. The lattice Boltzmann method uses D2Q9 lattice structure and BGK collision operator with single relaxation time. The solid wall boundary conditions used in this paper are based on the idea of bounceback of the nonequilibrium part of particle distribut...

We provide the first direct calculation of Knudsen layer (KL) thickness in rarefied gas flows based on ballistic molecular motions simulation Monte Carlo simulations. Calculations reproduce a linear relation between KL and mean free path (MFP) gas, which agrees with classical kinetic theory statement. The ratio MFP is only function model at slight flow gradients. However, high gradient surface ...