The rarefied gas effect on concentration slip and on heterogeneous combustion in microscale chemical reactors was investigated. First, a concentration slip model to describe the rarefied gas effect on the species transport in microscale chemical reactors was derived from the approximate solution of the Boltzmann equation. Second, the model was verified using the direct Monte-Carlo method for th...

A hybrid particle scheme is presented for the simulation of compressible gas flows involving both continuum regions and rarefied regions with strong translational nonequilibrium. The direct simulation Monte Carlo (DSMC) method is applied in rarefied regions, while remaining portions of the flowfield are simulated using a DSMC-based low diffusion particle method for inviscid flow simulation. The...

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 molecu...

The micro-scale gas flows are usually low-speed flows and exhibit rarefied gas effects. It is challenging to simulate these flows because traditional CFD method is unable to capture the rarefied gas effects and the direct simulation Monte Carlo (DSMC) method is very inefficient for low-speed flows. In this study we combine two techniques to improve the efficiency of the DSMC method. The informa...

Classical continuummethods break down for rarefied gas flows inmicro-channels. Twononcontinuumhydrodynamicmodels are investigated here: compressible Korteweg fluid-like andBiVelocity (VolumeDiffusion) hydrodynamicmodels. The pressure driven rarefied gasflow in a rectangularmicro-channel in thewhole range of Knudsen number is numerically considered. The Kortewegmodel shows improved results in co...

Classical continuummethods break down for rarefied gas flows inmicro-channels. Twononcontinuumhydrodynamicmodels are investigated here: compressible Korteweg fluid-like andBiVelocity (VolumeDiffusion) hydrodynamicmodels. The pressure driven rarefied gasflow in a rectangularmicro-channel in thewhole range of Knudsen number is numerically considered. The Kortewegmodel shows improved results in co...

A particle, shaped as an ellipsoid of revolution and rotating about an arbitrary axis, experiences a torque in a rarefied monatomic gas because of the impact with the gas atoms. This torque is calculated for the case where the linear dimensions of the ellipsoid are small compared with the mean free path of the gas. The interaction of the gas atoms with the ellipsoidal surface is taken into acco...

A recently established version of the discrete-ordinates method is used to develop a solution to a class of problems in the theory of rarefied-gas dynamics where temperature and density effects are coupled. In particular, accurate solutions for the temperature perturbation, the density perturbation, and the heat flux are developed and evaluated for the flow, described by the Bhatnagar, Gross, a...

the mixing behavior of the gas-liquid phase in three loop bioreactors was investigated. a gas-induced external airlift loop bioreactor (ealb), a forced-liquid vertical tubular loop bioreactor (vtlb) and a forced-liquid horizontal tubular loop bioreactor (htlb) were used for mixing studies as well as biomass production from natural gas. the effect of design parameters, riser to downcomer cross s...