Effects of Pressure Gradient Change on Flow and Heat Transfer in Backward-Facing Step Flow

Abstract

Backward-facing flows have been the subject of numerous experimental and numerical studies for computational fluid dynamics and heat transfer studies from past to present. The typical features of these flows are the separation of the flow after the abruptly changing channel height and the recombination of the formed flow if the channel length is long enough. In such flows, where we can see both laminar and turbulent flow examples, heat transfer also takes place due to the recombination of the flow. In this study, post-step recombination and heat transfer due to the channel geometry that narrows and expands towards the channel exit from a determined point before the step independent of the turbulence intensity in a closed channel were investigated. The results of an experimental study that is widely discussed in literature studies; it has been reached by using the Standard k ε model in ANSYS Fluent. After reaching the experimental data with the applied numerical model, the results obtained by using the narrowing and expanding channel geometry were examined. It has been determined that in cases where the pressure gradient effect decreases towards the channel exit, the re-unification region moves towards the channel exit and the heat transfer capacity decreases.