Among the few classes of computational approaches for examining rarefied gas dynamics, the most widely used technique for spatial scales relevant to suborbital spaceflight is the direct simulationMonte Carlo method. One area in which the direct simulation Monte Carlo method can be improved is the numerical modeling of the interactions between gas molecules and solid surfaces. Gas–surface intera...

Numerical meshes of both cork and carbon fibre ablative materials in their virgin and pyrolised states, with realistic porosity and tortuosity, have been created from micro-computed tomography (μCT) scans. The porosity of each material has been calculated from the μCT scans and used to extract smaller representative sample volumes to perform numerical simulations on. Direct simulation Monte Car...

It is well known that for increasingly rarefied flowfields, the predictions from continuum formulation, such as the Navier–Stokes equations lose accuracy. For the high speed diatomic molecular flow in the transitional regime, the inaccuracies are partially attributed to the single temperature approximations in the Navier–Stokes equations. Here, we propose a continuum multiple temperature model ...

Gas flows encountered in micro/nano scale devices are often low speed and non-continuum. The Direct Simulation Monte Carlo (DSMC), a popular molecular based simulation technique for rarefied gas, has proven to be inefficient in dealing with low-speed gas flows. In this paper, we present the Octant Flux Splitting Information Preserving DSMC (OSIP-DSMC) method as an efficient DSMC method for micr...

Two squeeze-film gas damping models are proposed to quantify uncertainties associated with the gap size and the ambient pressure. Modeling of gas damping has become a subject of increased interest in recent years due to its importance in micro-electro-mechanical systems (MEMS). In addition to the need for gas damping models for design of MEMS with movable micro-structures, knowledge of paramete...

A new approach to calculate the axially symmetric binary gas flow is proposed Dalton’s law for partial pressures contributed by each species of a binary gas mixture (argon and helium) is incorporated into numerical simulation of rarefied axially symmetric flow inside a rotating cylinder using the time relaxed Monte-Carlo (TRMC) scheme and the direct simulation Monte-Carlo (DSMC) method. The res...

The development of an information preservation (IP) method is described in this paper. This effort is aimed at increasing our understanding of rarefied gas behavior of subsonic, micro-scale gas flows. The IP method preserves macroscopic information of the flow in the simulated particles. It applies conservation laws for binary collisions of the particles following the movement in the DSMC metho...