Numerical Analyses on Velocity and Temperature Fields in the Recirculating Zone behind a Backward-Facing Step : the Influence of Reynolds Number

Abstract

Energy balance and its Reynolds number dependency are analysed in the recirculating zone behind a backward-facing step by using the standard k-ε model. By using a heat-line visualisation technique, the heat transfer between the main flow and the wall across the recirculating zone is shown to be divided into two processes: (1) heat transfer across the boundary layer formed by the backward flow along the wall and (2) heat transfer across the shear layer between the main flow and recirculating zone. Due to the difference between the Reynolds number dependency of these two mechanisms, the core temperature in the recirculating zone approaches the main flow temperature according to the increase of the Reynolds number.