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Explicitly Filtered LES of Single-Phase Compressible Flow

Radhakrishnan, Senthilkumaran and Bellan, J. (2012) Explicitly Filtered LES of Single-Phase Compressible Flow. In: 50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition. American Institute of Aeronautics and Astronautics , Reston, VA, Art. No. 2012-0182. ISBN 9781600869365. https://resolver.caltech.edu/CaltechAUTHORS:20190828-102318608

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Abstract

In Large Eddy Simulation (LES), it is often assumed that the filter width is equal to grid spacing. Predictions from such LES are grid-spacing dependent since any Subgrid Scale (SGS) model used in the LES equations is dependent on the resolved flow field which itself varies with grid spacing. Moreover, numerical errors affect the flow field, especially the smallest resolved scales. Thus, predictions using this approach are affected by both modeling and numerical choices. However, grid-spacing independent LES predictions unaffected by numerical choices are necessary to validate LES models through comparison with a trusted template. First, such a template is here created through Direct Numerical Simulation (DNS). Then, simulations are conducted using the conventional LES equations and also LES equations which are here reformulated so that the small-scale producing nonlinear terms in these equations are explicitly filtered (EF) to remove scales smaller than a fixed filter width; this formulation is called EFLES. The conventional LES solution is both grid-spacing and spatial discretization-order dependent, thus showing that both of these numerical aspects affect the flow prediction. The solution of the EFLES equations is grid independent for a high-order spatial discretization on all meshes tested. However, low order discretizations require a finer mesh to reach grid independence. With an eighth order discretization, a filter-width to grid-spacing ratio of two is sufficient to reach grid-independence, while a filter-width to grid-spacing ratio of four is needed to reach grid independence when a fourth or a sixth order discretization is employed. On a grid fine enough to be utilized in a DNS, the EFLES solution exhibits grid independence and does not converge to the DNS solution.


Item Type:Book Section
Related URLs:
URLURL TypeDescription
https://doi.org/10.2514/6.2012-182DOIArticle
ORCID:
AuthorORCID
Bellan, J.0000-0001-9218-7017
Additional Information:© 2012 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.
Other Numbering System:
Other Numbering System NameOther Numbering System ID
AIAA Paper2012-0182
DOI:10.2514/6.2012-182
Record Number:CaltechAUTHORS:20190828-102318608
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190828-102318608
Official Citation:Explicitly Filtered LES of Single-Phase Compressible Flow Senthilkumaran Radhakrishnan and Josette Bellan 50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition. https://doi.org/10.2514/6.2012-182
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:98308
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:28 Aug 2019 18:20
Last Modified:16 Nov 2021 17:38

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