Gas flows in microchannels and microtubes

Abstract

This study analyses compressible gas flows through microchannels or microtubes, and develops two complete sets of asymptotic solutions. It is a natural extension of the previous work by Arkilic et al. on compressible flows through microchannels. First, by comparing the magnitudes of different forces in the compressible gas flow, we obtain proper estimations for the Reynolds and Mach numbers at the outlets. Second, based on these estimations, we obtain asymptotic analytical solutions of velocities, pressure and temperature distributions of compressible gas flow inside the microchannels and microtubes with a relaxation of the isothermal assumption, which was previously used in many studies. Numerical simulations of compressible flows through a microchannel and a microtube are performed by solving the compressible Navier-Stokes equations, with velocity slip and temperature jump wall boundary conditions. The numerical simulation results validate the analytical results from this study.

Two-Dimensional Micro-Hartmann Gas Flows

“…The work in this paper is a natural extension from two previous work by Arkilic et al [1] and Cai et al [5]Along the same vein, the present study follows Cai's previous approach [5] for treatments of microchannel MGD flows. A few works appeared in recent years in the same area of MGD microchannel flow.…”

“…The flow is well approximated with a quasi-isothermal assumption. [5]As such, gas viscosity, μ, thermal conductivity, k, magnetic permeability, μ m , and electric conductivity, σ, are treated as constants. 3.…”

“…[4] Discussions of thermal heating effects are reported as well. [5] One important problem related to gas flow inside a microchannel is conductive gas flows under external magnetic and electric fields, or MagnetoGasDynamic(MGD) flows. These fields can significantly affect the internal gas flow field, while different placements of electric field enables the channel to perform as a generator, a pump, a flux meter, or an accelerator.…”

“…[8,9] There are some differences between the present approach and others: 1. Our study includes a governing equation for temperature necessitated by the Joule heating effects to obtain the temperature field; [5] by comparison, the past work completely neglects the energy equation. 2.…”

Permeability of Ablative Materials Under Rarefied Gas Conditions

“…It is clear that all simulations have the same inlet and outlet pressures. The pressure profiles deviate from the simple straight line that would be expected for a continuum gas flow, but they are also significantly different from the well known nonlinear pressure profiles in transition regime gas flows [32][33][34]. 1.32 × 10…”