Geometry of bluff body wakes

Abstract The attached recirculating wake zone has been experimentally investigated for spheres, spherical caps and circular discs normal to the flow. Tracer photography in a water tunnel was employed for the measurements. Results are presented over the range of Reynolds number from 20 to 400. The following wake properties are presented as a function of Reynolds number: angle of separation for spheres; wake length for spheres and discs, wake volume for all three types of body. The results for separation angle are in good agreement with the data available from the literature, both experimental and theoretical. Wake length results for spheres are also in agreement with published values and with values obtained from published numerical solutions of the equations of motion. Wake volume results for spheres are similarly in agreement with values calculated from published wake dimensions obtained both experimentally and theoretically. Spherical caps are found to have the wake volume either of discs if they are thin (h/D <0.3) or of spheres if they are thick (h/D > 0.6). Caps of intermediate thickness to diameter ratio show a transition between sphere‐like and disc‐like behavior. This behavior is explained in terms of the separation angle on spheres.