A Study on Velocity Profiles of Developing Laminar Oscillatory Flows in a Square Duct

Abstract

The entrance length Le of a laminar oscillatory flow in a square duct was defined as the maximum axial migration distance of fluid particles from the duct entrance. The entrance region was divided into three subregions, and the limits among them were determined according to the instantaneous axial position of a particle relevant to Le. Analytical solutions were presented for the cases where only a linearized axial equation of motion could reasonably be applied. For each subregion, the analytical solution was compared with the velocity profiles measured by means of a hot-wire anemometer. Close agreement of results was seen in each subregion.