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Motion of a binary gas mixture in a porous membrane with a straight channel


The diffusional baric effect at a porous barrier with a straight channel is investigated theoretically and experimentally with an arbitrary ratio of the channel and pore diameter to the free path length of molecules of the gas mixture.

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l, R:

length and radius of membrane


characteristic pore size

r0 :

radius of straight channel

N, rs :

number of channels of model set of capillaries per unit area of the porous medium and their radius


mean free path length

ūiz ch, ūiz p, ūiz M :

projection of mean velocity of motion of molecules of the i-th component in the channel, porous medium, and membrane, respectively, onto the membrane axis

p, T, n:

pressure, temperature, and number density of mixture particles

mi, di :

mass and diameter of molecules of the i-th component

ci :

concentration of i-th component of mixture

η12, ηi :

viscosity of mixture and its i-th component, respectively

D12, σ:

mutual diffusion coefficient and diffusional-slip coefficient


Boltzmann constant

Sch, SP, SM :

cross-sectional area of channel, porous medium, and membrane

Qch, QP, QM :

volume flow rate of gas mixture through channel, porous medium, and membrane

Qe :

experimental volume flow rate of gas mixture

KnP, Knch :

Knudsen number in pores and in channel

δ12P, δ12 ch :

inverse Knudsen number in pores and in channel



Δpm, tm :

maximum magnitude of baric effect and time for its attainment


chamber volume

Literature cited

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Additional information

Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 54, No. 5, pp. 725–732, May, 1988.

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Ivakin, B.A., Malakhin, V.M., Porodnov, B.T. et al. Motion of a binary gas mixture in a porous membrane with a straight channel. Journal of Engineering Physics 54, 480–486 (1988).

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  • Statistical Physic
  • Path Length
  • Pore Diameter
  • Free Path
  • Porous Membrane