ABSTRACT

The present contribution focuses on the modelling of the buoyancy production term in the transport equation for the dissipation of turbulent kinetic energy. The natural convection test case of Versteegh & Nieuwstadt (1999) is considered, which consists in a DNS of a differentially-heated, vertical-channel flow. Consistently with the underlying physics, it is found beneficial, contrary to the usual practise, to separately model the buoyancy and dynamic parts of the production of dissipation, in order to account for the increase of dynamic production and the variations of the thermal-to-mechanical time-scale ratio in the near-wall region.