Second order closure for stratified convection: bulk region and overshooting

Abstract

The parameterization of small-scale turbulent fluctuations in convective systems and in the presence of strong stratification is a key issue for many applied problems in oceanography, atmospheric science and planetology. In the presence of stratification, one needs to cope with bulk turbulent fluctuations and with inversion regions, where temperature, density -or both- develop highly non-linear mean profiles due to the interactions between the turbulent boundary layer and the unmixed -stable- flow above/below it. We present a second order closure able to cope simultaneously with both bulk and boundary layer regions, and we test it against high-resolution state-of-the-art 2D numerical simulations in a convective and stratified belt for values of the Rayleigh number, up to Ra = 10^9. Data are taken from a Rayleigh-Taylor system confined by the existence of an adiabatic gradient.

10 pages, 5 figures

References in corpus (5)

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• Energy transport, overshoot, and mixing in the atmospheres of M-type main- and pre-main-sequence objects
• Mixing in stratified gravity currents: Prandtl mixing length
• High resolution numerical study of Rayleigh-Taylor turbulence using a thermal lattice Boltzmann scheme
• Nonlinear diffusion model for Rayleigh-Taylor mixing