Application of the Stokes Drag on Spheroids to the Drag on Disks and Cylinders

Abstract

The measured drag forces on cylinders and disks obtained by Jayaweera and Cottis and by Kajikawa are compared with those computed for Stokes flow around equivalent spheroids. For both the disks and cylinders, comparisons an made both for flow parallel to and perpendicular to the solids' symmetry axes. The ratios of measured to Stokes drag forces range from 0.59 to 1.14 and cover Reynolds numbers ranging from 1.6 ? 10?3 to 2.0 ? 10?1. Thus these results allow for the convenient calculation, using the Stokes drag expression, of the terminal velocities of ice crystals falling in the atmosphere with major dimensions of up to a few tens of microns.