Microstructure of flow in a channel with low-profile spanwise ribs

Abstract

Abstract The paper presents the experimental data on velocity fluctuation spectra and reattachment lengths observed in turbulent flows past low-profile elements of discrete roughness mounted on the wall. The discrete roughness elements were shaped as semicircular spanwise ribs with the height of 2% of the hydraulic diameter of the channel. It has been revealed that such ribs make the velocity fluctuations increase manifold at the height of rib tops in the range of non-dimensional frequency St=0.6-1.2 that favors the reattachment length reduction and heat transfer augmentation.