Dynamic subgrid-scale scalar-flux model based on the exact rate of production of turbulent fluxes

Shujaut H. Bader and Paul A. Durbin
Phys. Rev. Fluids 5, 114609 – Published 19 November 2020

Abstract

A dynamic subgrid-scale (SGS) scalar-flux model, based on the exact rate of production of turbulent scalar fluxes, is proposed. The model is derived from an assumption that the pressure-scalar correlation in the equation for turbulent scalar flux is a vector that is approximately aligned with the scalar flux itself. The formulation then yields a tensor diffusivity which allows nonalignment of the SGS scalar fluxes with respect to the resolved scalar gradient. In contrast to eddy diffusivity models and to general gradient diffusion hypothesis models, for which the diffusivity tensor is symmetric, the present formulation produces an asymmetric diffusion tensor; for theoretical and experimental reasons, that tensor is known to be very asymmetric. The model contains a single coefficient, which is determined dynamically. The model is validated in fully developed turbulent channel flow and in separated and reattaching flow over a backstep.

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  • Received 19 April 2020
  • Accepted 27 October 2020

DOI:https://doi.org/10.1103/PhysRevFluids.5.114609

©2020 American Physical Society

Physics Subject Headings (PhySH)

Fluid Dynamics

Authors & Affiliations

Shujaut H. Bader* and Paul A. Durbin

  • Department of Aerospace Engineering, Iowa State University, Ames, Iowa 50011, USA

  • *shbader@iastate.edu
  • durbin@iastate.edu

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Issue

Vol. 5, Iss. 11 — November 2020

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