A gas kinetic scheme for hybrid simulation of partially rarefied flows

Colonia, S., Steijl, R. and Barakos, G. (2017) A gas kinetic scheme for hybrid simulation of partially rarefied flows. In: Knight, D., Bondar, Y., Lipatov, I. and Reijasse, P. (eds.) Progress in Flight Physics. EDP Sciences, pp. 301-326. ISBN 9785945882157 (doi: 10.1051/eucass/2016090301)

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Approaches to predict flow fields that display rarefaction effects incur a cost in computational time and memory considerably higher than methods commonly employed for continuum flows. For this reason, to simulate flow fields where continuum and rarefied regimes coexist, hybrid techniques have been introduced. In the present work, analytically defined gas-kinetic schemes based on the Shakhov and Rykov models for monoatomic and diatomic gas flows, respectively, are proposed and evaluated with the aim to be used in the context of hybrid simulations. This should reduce the region where more expensive methods are needed by extending the validity of the continuum formulation. Moreover, since for high-speed rare¦ed gas flows it is necessary to take into account the nonequilibrium among the internal degrees of freedom, the extension of the approach to employ diatomic gas models including rotational relaxation process is a mandatory first step towards realistic simulations. Compared to previous works of Xu and coworkers, the presented scheme is de¦ned directly on the basis of kinetic models which involve a Prandtl number correction. Moreover, the methods are defined fully analytically instead of making use of Taylor expansion for the evaluation of the required derivatives. The scheme has been tested for various test cases and Mach numbers proving to produce reliable predictions in agreement with other approaches for near-continuum flows. Finally, the performance of the scheme, in terms of memory and computational time, compared to discrete velocity methods makes it a compelling alternative in place of more complex methods for hybrid simulations of weakly rarefied flows.

Item Type:Book Sections
Additional Information:Paper presented at the 6th European Conference for Aeronautics and Space Sciences (EUCASS 2015), Krakow, Poland, 29 June - 3 July 2015.
Glasgow Author(s) Enlighten ID:Barakos, Professor George and Steijl, Dr Rene and Colonia, Mr Simone
Authors: Colonia, S., Steijl, R., and Barakos, G.
College/School:College of Science and Engineering > School of Engineering > Autonomous Systems and Connectivity
Publisher:EDP Sciences
Copyright Holders:Copyright © 2017 The Authors
First Published:First published in Progress in Flight Physics 9:301-326
Publisher Policy:Reproduced under a Creative Commons License

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