On the laminar flow over a cylindrical roughness element

Abstract

A direct comparison of experimental and simulation results of two flows, a laminar boundary layer developing on a flat heated plate and the interaction of a laminar boundary layer with a single cylindrical roughness element with a height of the same order of the boundary-layer displacement thickness, is presented. The experiments were performed in a water channel using temperature-sensitive paint (TSP) and the simulations used the Ansys Fluent computational fluid dynamics software. The numerical simulations supplement the experimental data, allowing for a direct comparison with the experiment, and they provide information not easily accessible from the experiment. In the case of the laminar boundary layer developing over a heated flat plate, experimental measurements and simulation results of the surface temperature show strong agreement and a correlation coefficient for the two temperature fields of 0.98 is obtained. In the case of a laminar boundary layer interacting with a low aspect ratio roughness element at a roughness Reynolds number Re = 355, a complex vortical structure is observed. Again good agreement between the experimental and simulation results is obtained with a correlation coefficient of 0.95 for the respective temperature fields.