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PASSIVE SCALAR FLUX MODELLING FOR CFD

Carl-Maikel Hogstrom
Aeronautics Division, FFA Swedish Defence Research Agency (FOI) SE-172 90 Stockholm, Sweden

Stefan Wallin
Linne FLOW Center, Department of Mechanics Royal institute of technology Osquars Backe 18, Stockholm, Sweden

Arne V. Johansson
Linne FLOW Centre, Dept. of Mechanics, Royal Institute of Technology SE-100 44 Stockholm, Sweden

Аннотация

Modelling of passive scalar transport in turbulent flows is considered, with the scope of testing an additional simplification of the explicit algebraic model (EASFM), recently proposed by Wikstrom, Wallin and Johansson (Phys. Fluids, 2000). Here the possibility to use a constant value for the turbulent scalar to dynamical time-scale ratio is examined, with the aim of avoiding two additional transport equations needed in the original model. The simplified EASFM is calibrated against homogeneous shear flow and turbulent channel flow. A model was added for considering the neglected diffusion terms in regions with low turbulence production. The resulting model was found to be able to predict all of the scalar flux components well, even though the scalar to dynamical time-scale ratio needed in the model, was assumed to be equal to a constant.