Sweeping has no effect on renormalized turbulent viscosity

We perform renormalization group analysis (RG) of the Navier-Stokes equation in the presence of constant mean velocity field $\mathbf U_0$, and show that the renormalized viscosity is unaffected by $\mathbf U_0$, thus negating the ``sweeping effect", proposed by Kraichnan [Phys. Fluids {\bf 7}, 1723 (1964)] using random Galilean invariance....

A Unified Shell model for Buoyancy-Driven Turbulence

We construct a unified shell model for stably stratified and convective turbulence. Shell model simulation of stably stratified flow in turbulent regime exhibit Bolgiano-Obukhbov (BO) scaling in which the kinetic energy spectrum varies as $k^{-11/5}$. However, simulation of convective turbulence shows Kolmogorov's spectrum. These results are...

Energy transfers in small-scale and large-scale dynamos

We study energy transfers during magnetic energy growth in small-scale and large-scale dynamos. We perform direct numerical simulations for magnetic Prandtl number Pm =20 and 0.2 in a periodic box on 1024^3 grid. Energy fluxes and shell-to-shell energy transfers indicate that in small-scale dynamo for Pm =20, the magnetic energy growth takes...