The Resistance of Hairy Body Moving in Air

Abstract

Hydrodynamical properties of hairy body are studied by using plane, hemi-spherical models bristled with thistle (sawa-azami) pappi which are cylindrical. By measuring the terminal velocity and introducing the effective projected area, the drag coefficient is determined. Rey-nolds number is varied by the mass of center of the model. The drag is found approximately proportional to the ath power of the terminal velocity. The relation of the exponent a to the number of bristle is shown by a figure. The drag coefficient at Reynolds number 300 is nearly constant, is independent of the number of bristle, but at 2000, it decreases slightly with the latter. The drag of a plane model is calculated by using the theoretical drag coef-ficient of an infinitely long cylinder and compared with the experimental value.