Assessment of Numerical Dissipation in Implicit LES of Turbulent Rayleigh-Bénard Convection

Abstract

The methodology to quantify the numerical dissipation in implicit/explicit LES and under-resolved DNS (UDNS) based on the balance of the kinetic energy equation by Cadieux et al. [1] has been examined for Rayleigh-Bénard convection (RBC) in this study. To this end, this approach has been extended here for scalar transport (i.e., thermal variance) in addition to kinetic energy since momentum and thermal transport are coupled due to buoyancy forces in the RBC. Accordingly, the effect of grid resolution on numerical dissipation has been analysed in the context of implicit LES/UDNS in order to evaluate the accuracy of the simulations. It has been found that the aforementioned method works sufficiently well for quality assessment of UDNS of RBC.