Abstract
In the present contribution attention is focused to extend the application of multifluid descriptions to rarefied conditions for the first time. To this aim, a multifluid Maxwell model and a multifluid Smoluchowski model are proposed for near wall behavior of the constituents of a rarefied gas mixture. Afterwards, multifluid balance equations in conjunction with these boundary conditions are solved for some slip flows of binary gas mixtures between parallel plates. The corresponding results are compared with those of a previously developed Navier–Stokes solver. Inspection of the results indicates that while the Navier–Stokes equations may lose their accuracy under high rarefaction, non–equilibrium features are properly captured by developed multifluid description. This successful method is thereafter utilized to discuss the consequences of velocity–slip, the tangential–momentum–accommodation coefficient, and mass disparity of the mixture constituents on the degree of non–equilibrium between the constituents of the gas mixtures between parallel plates.
Highlights
Rarefied gas flows are generally encountered in small geometries, such as micro–sized devices, and in low pressure applications, such as high–altitude aerodynamics
SIMULATION RESULTS simulation results are presented for rarefied gas mixture flows between parallel plates
It must be noted that simultaneous use of the proposed velocity–slip and temperature–jump boundary conditions for both sets of the balance equations is beyond the current computational analysis
Summary
Rarefied gas flows are generally encountered in small geometries, such as micro–sized devices, and in low pressure applications, such as high–altitude aerodynamics. In spite of previous advancements in the analysis of rarefied gas mixtures flows, multifluid models have not been employed for the description of these flow fields yet This approach has a wide range of application for the simulation of gas–gas, gas–liquid, and solid–liquid mixture problems [20,21,22,23,24]. A multifluid model with previous success in the simulation of monoatomic gases in the continuum flow regime [25,26,27,28] is applied to some slip flows of binary gas mixtures between parallel plates This is attained by the application of separate velocity–slip and temperature–jump boundary conditions for each of the constituents. To overcome the aforementioned shortcomings, in this contribution, a multifluid Maxwell model and a multifluid Smoluchowski model are proposed as extensions of the Maxwell [29] and Smoluchowski [30] boundary conditions for separate component species in multifluid descriptions
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