Scale-space energy transport in anisotropic inhomogeneous buoyancy-driven turbulent flows

Abstract: In this article, we introduce a new mathematical framework that can describe the budget of turbulence kinetic energy and heat transfer in both physical space and scale space of turbulence. We derived two exact transport equations for inhomogeneous and anisotropic buoyancy-driven incompressible turbulent flow. The two equations are the turbulent kinetic energy transport equation and the turbulent heat flux density transport equation. These equations are derived from the governing Navier-Stokes equation and two-point correlations. Analogous to the energy spectrum and heat flux spectrum for homogeneous isotropic turbulence, energy density, and heat flux density introduced in this paper describe the energy and heat flux corresponding in various scales and the transport across physical and scale space for inhomogeneous anisotropic turbulent flows. The proposed equations are used to post-process a turbulent Rayleigh-B\'enard convection flow dataset. Specifically, production, dissipation, interscale transport, and buoyancy terms are evaluated, and the contribution from inhomogeneity is quantified.