Kinetic models and gas-kinetic schemes for hybrid simulation of partially rarefied flows

Colonia, S., Steijl, R. and Barakos, G. (2016) Kinetic models and gas-kinetic schemes for hybrid simulation of partially rarefied flows. AIAA Journal, 54(4), pp. 1264-1276. (doi:10.2514/1.J054137)

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Abstract

Approaches to predict flowfields that display rarefaction effects incur a cost in computational time and memory that is considerably higher than methods commonly employed for continuum flows. For this reason, to simulate flowfields 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 monatomic and diatomic gas flows, respectively, are proposed and evaluated, with the aim of being 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, because, for rarefied gas flows at high velocities, 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 with rotational relaxation is a mandatory first step toward realistic simulations. Compared to the previous works the presented scheme is defined directly on the basis of kinetic models that 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:Articles
Status:Published
Refereed:Yes
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 > Aerospace Sciences
Journal Name:AIAA Journal
Publisher:American Institute of Aeronautics and Astronautics
ISSN:0001-1452
ISSN (Online):1533-385X
Copyright Holders:Copyright © 2016 American Institute of Aeronautics and Astronautics
First Published:First published in AIAA Journal 54(4):1264-1276
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher.

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