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arXiv · 1902.06556

Contrasting turbulence in stably stratified flows and thermal convection

Mahendra K. Verma
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Abstract

In this paper, the properties of stably stratified turbulence (SST) and turbulent thermal convection are contrasted. A key difference between these flows is the sign of the kinetic energy feed by buoyancy, $\mathcal{F}_B$. For SST, $\mathcal{F}_B < 0$ due to its stable nature; consequently, the kinetic energy flux $Π_u(k)$ decreases with wavenumber $k$ that leads to a steep kinetic energy spectrum, $E_u(k) \sim k^{-11/5}$. Turbulent convection is unstable, hence $\mathcal{F}_B > 0$ that leads to an increase of $Π_u(k)$ with $k$; this increase however is marginal due to relatively weak buoyancy, hence $E_u(k) \sim k^{-5/3}$, similar to that in hydrodynamic turbulence. This paper also describes the conserved fluxes for the above systems.

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Mahendra K. Verma. 2019-02-18. Contrasting turbulence in stably stratified flows and thermal convection. https://doi.org/10.1088/1402-4896%2Fab022a

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