Measurements and computations of mass flow and momentum flux through short tubes in rarefied gases

Abstract

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“…Also, W is increased as the length of the channel is decreased and the rarefaction parameter is increased. More speci¦cally, the §ow rate for δ 0 = [0.1, 1] increases very slowly and then more rapidly for δ 0 = [1,10]. Additional simulations have been performed with Z = 6 for δ 0 = 1 and L/R = 1 and 5 showing very small e¨ect on the §ow rates.…”

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Hybrid modeling of time-dependent rarefied gas expansion

“…These volumes are large enough to ensure uniform conditions at the boundaries but much smaller than the volumes of chambers A and B. The case of purely pressure driven flow, i.e., when the temperature in the two chambers is the same, has been thoroughly studied via kinetic theory and numerical results in the whole range of the Knudsen number have been reported in the literature, based on both the DSMC method [14][15][16][17] and on deterministic kinetic modeling. 22,23,25 The dimensionless solution depends on three parameters, namely, the reference Knudsen number, the ratio of the downstream over the upstream pressure, and the ratio of the length over the radius of the tube.…”

“…[3][4][5][6][7][8][9][10][11][12] In the case of channels of finite length, in addition to the above parameters, the pressure ratio and the length of the channel, as well as the end effects, are introduced in the investigation, increasing significantly the computational effort. However, both the direct simulation Monte Carlo (DSMC) method [13][14][15][16][17] and deterministic linear and nonlinear kinetic modeling [18][19][20][21][22][23][24][25] have been successfully applied to provide accurate results.…”