Abstract
Using highresolution direct numerical simulation and arguments based on the kinetic energy flux Πu, we demonstrate that, for stably stratified flows, the kinetic energy spectrum Eu(k)∼k11/5, the potential energy spectrum Eθ(k)∼k7/5, and Πu(k)∼k4/5 are consistent with the BolgianoObukhov scaling. This scaling arises due to the conversion of kinetic energy to the potential energy by buoyancy. For weaker buoyancy, this conversion is weak, hence Eu(k) follows Kolmogorov's spectrum with a constant energy flux. For RayleighBénard convection, we show that the energy supply rate by buoyancy is positive, which leads to an increasing Πu(k) with k, thus ruling out BolgianoObukhov scaling for the convective turbulence. Our numerical results show that convective turbulence for unit Prandt number exhibits a constant Πu(k) and Eu(k)∼k5/3 for a narrow band of wave numbers. © 2014 American Physical Society.
Original language  English 

Article number  023016 
Number of pages  9 
Journal  Physical Review E  Statistical, Nonlinear, and Soft Matter Physics 
Volume  90 
DOIs  
Publication status  Published  25 Aug 2014 
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Profiles

Abhishek Kumar
 Research Centre for Fluid & Complex Systems  Assistant Professor
Person: Teaching and Research