Flow in a channel with obstacles of different scales: A detached rib and a forward-facing step

Abstract

A numerical study of the flow in a channel with a forward- facing step was carried out. A single disconnected rib 3 mm high served as a passive control element in the range of Reynolds numbers from 2700 to 16400. The rib was installed at a distance to the ledge from 1.6 to 0.8 calibers at a height of 0.2 to 1 caliber. The introduction of an edge transforms the flow in front of the step. A tear-off area is created behind the rib. In cases of a high-lying rib, the separation area behind the shoulder becomes larger than the unregulated case, which leads to a loss of total pressure and an increase in the hydraulic resistance of the channel. Thermal-hydraulic efficiency was assessed; installing the fin at a close distance from the wall showed the best result