DNS and regularization modeling of a turbulent differentially heated cavity of aspect ratio 5

This work is devoted to the study of turbulent natural convection flows in differentially heated cavities. The adopted configuration corresponds to an air-filled (Pr = 0.7) cavity of aspect ratio 5 and Rayleigh number Ra = 4.5 × 1010 (based on the cavity height). Firstly, a complete direct numerical simulation (DNS) has been performed. Then, the DNS results have been used as reference solution to assess the performance of symmetry-preserving regularization as a simulation shortcut: a novel class of regularization that restrain the convective production of small scales of motion in an unconditionally stable manner. In this way, the new set of equations is dynamically less complex than the original Navier–Stokes equations, and therefore more amenable to be numerically solved. Direct comparison with the DNS results shows fairly good agreement even for very coarse grids.