Thermocline dynamics in a thermally stratified store

Analysis of a stratified store thermocline entrainment process is done by a side-by-side comparison of experiments and a direct numerical simulation. The experimental and numerical analyses are shown to be complementary; wher e the experiment is a true realisation of the thermocline entrainment proce ss, the numerical simulation provides the temporal and spatial resolution f or detailed analysis. The agreement between both is good. It appears that d uring collision of the buckling jet with the thermocline inhomogeneous pene tration and back flow occur, At the point where the jet flows back into the bottom layer, upper-layer fluid is dragged into the bottom layer. After de tachment, the dragged-down fluid filament becomes unstable due to overturni ng motions, resulting in Kelvin-Helmholtz-like waves. Subsequently the flui d filament is completely mixed with bottom-layer fluid by the action of str etching- and-folding stimulated diffusion. From a comparison between 2D- an d 3D-simulation results it appeared that for store optimisation 2D-numerica l simulations provide sufficient accuracy. (C) 2001 Published by Elsevier S cience Ltd.