WALL EFFECTS ON THE MOTION OF A ROLLING SPHERE IN A CLOSELY FITTING TUBE.

The retarding wall effects on the rolling motion of a descending sphere in a liquid contained in an inclined tube have been measured when the tube diameter is just larger than the diameter of the sphere. In the temperature range 353. 15-463. 15 K, the experimental data for the parameter K (the drag coefficient multiplied by the Reynolds number) were in much better agreement with the Lewis equation than with other proposed equations. For a d/D ratio of more than 0. 707 the values of K in the Stokes region and for a sphere diameter giving Reynolds numbers between 336 and 2285 were virtually the same.