Explicit algebraic Reynolds stresses and scalar fluxes for density-stratified shear flows

D Violeau (1)

1 EDF R&D - EDF R&D

An Explicit Algebraic Model for Reynolds stresses and active scalar turbu-lent fluxes is proposed for simply-stratified, stable shear flows like atmospheric boundary layers of estuaries, including buoyant effects due to density variations (temperature, salinity). Under equilibrium assumptions, this models leads to explicit functions of the gradient Richardson number Ri that model the damp-ing of the eddy viscosity and eddy diffusivity coefficients. The present model is compared to other existing theoretical approaches, as well as experimental ob-servations, with satisfactory agreement. The evolution of the turbulent Prandtl number as a function of Ri is correctly predicted and its neutral value is consis-tent with existing values in the literature. The behaviour of the model predicts that internal waves are responsible for momentum diffusion at large Ri, con-sitently with recent publications. The properties of turbulence anisotropy are briefly investigated.

Mots clés: turbulence; stratified flow; buoyancy; EARSM; Reynolds stresses; heat flux

Domaines: Mécanique des fluides [physics.class-ph]

D Violeau. Explicit algebraic Reynolds stresses and scalar fluxes for density-stratified shear flows. Physics of Fluids, 2009, 21, pp.35103. ⟨10.1063/1.3081552⟩. ⟨hal-01097837⟩