Macroscopic and kinetic modelling of rarefied polyatomic gases

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dc.contributor.authorRahimi, Behnam
dc.contributor.authorStruchtrup, Henning
dc.date.accessioned2017-06-12T13:40:16Z
dc.date.available2017-06-12T13:40:16Z
dc.date.copyright2016en_US
dc.date.issued2016
dc.description.abstractA kinetic model and corresponding high-order macroscopic model for the accurate description of rarefied polyatomic gas flows are introduced. The different energy exchange processes are accounted for with a two term collision model. The proposed kinetic model, which is an extension of the S-model, predicts correct relaxation of higher moments and delivers the accurate Prandtl (Pr) number. Also, the model has a proven linear H-theorem. The order of magnitude method is applied to the primary moment equations to acquire the optimized moment definitions and the final scaled set of Grad’s 36 moment equations for polyatomic gases. At the first order, a modification of the Navier–Stokes–Fourier (NSF) equations is obtained. At third order of accuracy, a set of 19 regularized partial differential equations (R19) is obtained. Furthermore, the terms associated with the internal degrees of freedom yield various intermediate orders of accuracy, a total of 13 different orders. Thereafter, boundary conditions for the proposed macroscopic model are introduced. The unsteady heat conduction of a gas at rest is studied numerically and analytically as an example of a boundary value problem. The results for different gases are given and effects of Knudsen numbers, degrees of freedom, accommodation coefficients and temperature-dependent properties are investigated. For some cases, the higher-order effects are very dominant and the widely used first-order set of the NSF equations fails to accurately capture the gas behaviour and should be replaced by the proposed higher-order set of equations.en_US
dc.description.reviewstatusRevieweden_US
dc.description.scholarlevelFacultyen_US
dc.description.sponsorshipNSERC Discovery Granten_US
dc.identifier.citationRahimi, B., & Struchtrup, H. (2016). Macroscopic and kinetic modelling of rarefied polyatomic gases. J. Fluid Mechanics, Vol. 806, pp. 437-505.en_US
dc.identifier.urihttps://doi.org/10.1017/jfm.2016.604
dc.identifier.urihttp://hdl.handle.net/1828/8270
dc.language.isoenen_US
dc.publisherJournal of Fluid Mechanicsen_US
dc.titleMacroscopic and kinetic modelling of rarefied polyatomic gasesen_US
dc.typePostprinten_US

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