Tensorial time scale in turbulent gradient transport of Reynolds stresses

On the notion that the Reynolds stresses are transported with different time scales depending on the transport direction, the third-order velocity correlations are represented by a new turbulent gradient transport model with a tensorial Lagrangian time scale. In order to verify the proposed model, DNS data are first obtained in a turbulent channel flow at Reτ=180 and 300, and tensorial Lagrangian time scales are computed. The present model predictions are compared with direct numerical simulation data and those predicted by the third-order turbulent transport model of Hanjalic and Launder that uses a scalar time scale. The result demonstrates that the Reynolds stresses are indeed transported with different time scales depending on the transport direction.