Heat and mass fluxes across density interfaces in a grid-generated turbulence

We present heat and salt fluxes measurements across a single density-stratified interface in a grids-generated turbulence system. The turbulent field is measured in a homogeneous medium (water) by Particle Image Velocimetry (PIV). Stratifications have been followed in time by recording the vertical temperature and density profiles. Measured buoyancy heat and mass fluxes show two different behaviors similar to that in double diffusive convection systems. This was also highlighted by measurement of entrainment rate near the interface, which showed that entrainment depends on the diffusivity for high Richardson number Ri. For low Ri, molecular diffusion has less effect on the transport process than turbulent mixing.