Prandtl number effects on the decaying and the forced turbulence in stratified fluids

etc15 Tracking Number 409

Effects of high-Prandtl number density-stratifying scalar, i.e., active scalar, on decaying and forced turbulence in stratified fluids are investigated by numerical simulations. In decaying turbulence, potential energy spectrum of the high-Prandtl number active scalar (Pr=6) agrees with the kinetic energy spectrum even at small scales. In forced steady turbulence, these two spectra again approach each other at small scales. These phenomena, which are in disagreement with the Batchelor scaling for a high-Schmidt number passive scalar, occur at scales even smaller than the Ozmidov scale, suggesting that these effects would not be negligible in general.