The Influence of the Recirculation Region: A Comparison of the Convective Heat Transfer Downstream of a Backward-Facing Step and Behind a Jet in a Crossflow

Abstract

Convective heat transfer is examined in two typical examples of separated flows, namely, the flow over a backward-facing step and a two-dimensional jet entering a crossflow. Local Nusselt numbers were determined in and behind the recirculation region. The main parameters influencing the heat transfer, the Reynolds number, and the momentum flux ratio of the jet and the crossflow have been varied over a wide range. In addition to heat transfer measurements, the flow field has been documented using an LDA system and oil film technique. The static pressure distribution at the wall within the separated flow is also given. The measurements are compared with the results of a numerical code, based on a finite volume method, where the well known k-ε model is employed. The differences in Nusselt numbers predicted with one- and two-layer models are shown to demonstrate the influence of wall functions on heat transfer. The numerical and experimental results are compared with available data, and the differences and similarities in the heat transfer behavior of separated flows are discussed.