Numerical simulation of the turbulent convective buoyant flow of sodium over a backward- facing step

摘要

A forced convective and a buoyancy-aided turbulent liquid sodium flow over audbackward-facing step with a constant heat flux applied on the indented wall is simulated.udLinear eddy viscosity models are used for the Reynolds stresses. Turbulent heat fluxes areudmodelled with a single gradient diffusion hypotheses with two different approaches to evaluateudthe turbulent Prandtl number. Moreover, the influence of turbulence on heat transfer to sodiumudis also assessed through simulations with zero turbulent thermal diffusivity. The results areudcompared with DNS data from literature. The velocity and turbulent kinetic energy profilesudpredicted by all models are in good agreement with the DNS data. The local Nusselt numberudtrend is qualitatively well captured, however, its magnitude is underestimated by all modelsudfor the mixed convection case. For forced convection, the heat transfer is overestimated by alludheat flux models. The simulation with neglected turbulent heat transfer shows the best overalludagreement for the forced convection case. For the mixed convection best agreement is obtainedudusing a correlation to locally evaluate the turbulent thermal diffusivity.