Mass transfer by a cylinder rotating in a fluid

The plane problem of the potential irrotational motion of an ideal fluid, caused by a cylinder rotating about a fixed axis parallel to the generatrix, is considered. It is shown that the average fluid velocity far from the cylinder decreases in proportion to the fifth power of the distance from the cylinder, and, by a special choice of the position of the fixed axis, in proportion to the seventh power. An exact solution of the problem is presented for an elliptic cylinder.