DNS study on investigation of heat transfer structure in turbulent backward-facing step flow

In this study, DNS is carried out to investigate turbulent heat transfer in a backward-facing step flow. In DNS, the Reynolds number based on step height and inlet bulk velocity is 2835, and the Prandtl number is 0.71, assuming air. As a result of DNS, the reattachment length is x/H = 6.35, and the recirculation region with a secondary vorticity near the corner behind the step is clearly observed. As for the thermal field, isothermal wall (ITW) and isoflux wall (IFW) conditions are arranged on the wall behind the step. In both cases, heat transfer phenomena are enhanced near the reattachment point, while suppressed upstream in the recirculation zone. It is found that ITW condition gives greater local Stanton number around the reattachment point than that of IFW.