Rarefied Gas Flow through Porous Media: Experiments and Numerical Simulation

In this paper we present the results of an experimental analysis concerning non-isothermal gas flow through a porous medium made of a packed bed of spheres. This problem is prototypal for more complex geometries which can be found in Micro Electro-Mechanics Systems (MEMS) where the heat transfer is a crucial issue. The characteristics length can be so tiny that gas flow regime could fall in almost rarefied regime where the continuum procedures are not valid. The experimental investigation covers a regime which spans from the continuum to the rarefied one and the Knudsen number varies from 0.0054 to 2.9. In particular here are reported results concerning gas flows through two concentric cylinders with surfaces at given temperatures. The mass flow rate and the radial and longitudinal distributions of the temperature are presented for different values of the Knudsen number. Finally some comparisons with numerical predictions are provided and discussed thoroughly.