Abstract

Regimes of convective entrainment in linearly and discretely stratified fluids are investigated by means of a high-resolution LES in conjunction with relevant data from atmospheric, laboratory, numerical, and analytical studies of penetrative convection. Relationships between parameters of entrainment in the discretely stratified fluid are shown to be rather different to their counterparts in t...

The strength of diapycnal mixing by small-scale motions in a stratified fluid is investigated through changes to the mean buoyancy profile. We study the mixing in laboratory experiments in which an initially linearly stratified fluid is stirred with a rake of vertical bars. The flow evolution Ž . depends on the Richardson number Ri , defined as the ratio of buoyancy forces to inertial forces. A...

Direct numerical simulations of the time evolution of homogeneous stably stratified shear flows have been performed for mean flow Richardson numbers in the range from 0.075 to 1.00 and for Prandtl numbers ranging from 0.1 to 2. The local or instantaneous results indicate that when the turbulent Froude number FrT = 1 the peak value of mixing efficiency is Rf ≈ 0.25, a result independent of the P...