A computational simulation of heat transfer to separation air flow in a concentric pipe

Abstract

Separation and reattachment of air flow through a sudden expansion in an annular passage is investigated. Backward facing steps play a vital role in the design of many heat related applications where heat transfer is concerned. In the present work, numerical simulation is performed using computer fluid dynamics package (Fluent) to study the effect of step flow in an annular passage. The obtained results are compared with the preliminary experimental findings. The flowing fluid was heated uniformly from the beginning of the expansion. Constant heat flux approach was considered for the heat transfer investigation. Annular pipe flow system having step ratio of d/D = 1.8 was considered where d and D representing the diameter of the pipe before and after expansion. Numerical simulation reviews that the reattachment point extends further with the increase of velocity for different occasions. Finally, the local Nusselt number (Nu) increases with the increase of Reynolds number (Re).