Analysis of Poiseuille and thermal transpiration flows for arbitrary Knudsen numbers by a modified Knudsen number expansion method and their database.

Modeling of Thermal Transpiration Flows for Knudsen Compressor Optimization

Rarefied gas flows through two-dimensional finite length capillaries are studied numerically with the goal of performance optimization of a nanomembrane-based Knudsen compressor. Both density and temperature gradient driven flows are considered in a wide range of Knudsen numbers from 0.05 to 75. The length-to-height ratios from 5 to 30 were examined. Three different wall temperature distributio...

A diffusive information preservation method for small Knudsen number flows

Keywords: DSMC IP Molecular diffusion Time step Cell size a b s t r a c t The direct simulation Monte Carlo (DSMC) method is a powerful particle-based method for modeling gas flows. It works well for relatively large Knudsen (Kn) numbers, typically larger than 0.01, but quickly becomes computationally intensive as Kn decreases due to its time step and cell size limitations. An alternative appro...

Energy Conversion using Thermal Transpiration : Optimization of a Knudsen

Knudsen compressors are devices without any moving parts that use the nanoscale phenomenon of thermal transpiration to pump or compress a gas. Thermal transpiration takes place when a gas is in contact with a solid boundary along which a temperature gradient exists. If the characteristic length scale is on the order of, or smaller than, the molecular mean free path, then the gas flows from cold...

A slip model for rarefied gas flows at arbitrary Knudsen number

Hybrid Particle-Continuum Simulations of Low Knudsen Number Hypersonic Flows

A modular particle-continuum (MPC) numerical method is used to simulate steady-state hypersonic flows which exhibit local regions of non-equilibrium embedded within mainly continuum flow fields. The MPC method loosely couples direct simulation Monte Carlo (DSMC) and Navier-Stokes (NS) methods which operate in different regions, use different mesh densities, and are updated using different sized...