The effects of turbulence and surface roughness on the drag of a cylinder

Abstract

Experiments have been made on that type of flow around a circular cylinder which is peculiarly sensitive to changes in Reynolds' number and for which the drag coefficient falls from 0.6 to 0.2 approximately. A study has been made of the effects on the drag of methodical changes in a turbulence artificially created in the general stream, in the roughness of the entire surface, and finally in the size of the local excrescencies formed by generator wires. These methodical changes are shown to produce orderly changes in the drag, and it is concluded that the flow considered although sensitive to such extraneous disturbances is not of a critical nature.