Analytical Modeling of Mean Pressure Distribution around a Two-Dimensional Circular Cylinder at High Reynolds Numbers

摘要

Two analytical models which describe the mean flow pressure distribution around a two dimensional circular cylinder at high Reynolds numbers are presented. The first model reproduces the cylinder and the wake region using a conformal mapping technique, whereas the second model describes the cylinder and the wake boundaries by linear segments of distributed vorticity (panel method). Neither model considers the flow field within the wake region. Only the external potential flow is studied. The input data for the two models, namely the base pressure and the position of the separation point, are provided by experimental results which are also compared with the computed pressure distribution. Both models lead to a computed pressure distribution which is generally in good agreement with the experimental data when considering a smooth cylinder. However, only the second model provides satisfactory matching in the case of cylinders with surface roughness where the boundary layer thickness has a strong influence on the location and the level of the peak suction as well as on the pressure rise which follows up to separation. The second model allows the boundary layer effects to be taken into account by adding to the geometrical shape of the cylinder the displacement thickness of the layer.