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A-PRIORI ANALYSIS OF A LES MODEL FOR SCALAR FLUX BASED ON INTERSCALE ENERGY TRANSFER

Markus Klein
Institut fur Mathematik und Rechneranwendung Universität der Bundeswehr München W.-Heisenberg-Weg 39, Neubiberg, Germany

Christoph Wolff
Fakultät für Luft- und Raumfahrttechnik, Universität der Bundeswehr München, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany

Eike Tangermann
Institut für Mathematik und Rechneranwendung, Universitat der Bundeswehr Munchen Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany

Abstract

Fluid mixing by turbulent motion occurs in many technical devices and has a strong impact on mass transfer, heat-transfer and chemical reaction (see e.g. Peng and Davidson (2002), Younis et al. (2005), Rossi (2010)). In Large Eddy Simulation (LES) the turbulent subgrid flux has to be modeled. Many simulations for heat or mass transfer rely on the classical linear eddy diffusivity approach which is in many cases not appropriate. As an example Fig.1 shows that even the simple plane jet shear flow considered in this work features counter-gradient transport. Similar to momentum transport in LES, the scale similarity model for SGS scalar flux is known to correlate well with the stresses evaluated from DNS (Peng and Davidson (2002)). However the model does not provide enough dissipation. Recently Anderson and Domaradzki (2012) analysed the interscale energy transfer of the scale similarity model in the context of momentum transport and, based on the results, proposed a new SGS model. In the present work this model will be modified to account for LES scalar fluxes. It will be analysed a-priori using a newly generated plane jet DNS database at Re=10000.