Гидродинамика

450 ON SNOWDRIFTS vortex E (Fig. 3) and its image G in the circle ABB'A'. By the letters e and g are denoted the distances of a point of the liquid from the points E and G. If the strength of the vortex k and its polar coordinates r — OE and Q are determined by formu­ lae (20) and (16), then the vortex E will be stationary and the motion defined by the current function 'I'o + 'l'i will be steady; the vorticity will be и — ^ motion there will exist two critical points, P and Q, at which the velocity will be zero— one in front of the cylinder, and the other in the rear of the cylinder. The lines of flow will be given by the equation ( ] ; o- | -= const, and the dividing line of flow, which in this case also will have two horizontal asymptotes, will divide all lines of flow into six groups: the upper lines of flow above the curve DPAA'D', the lower lines of flow, beneath the curve CPBB'QC, the closed lines of flow on the leeward side, bounded by th& contour APE, the closed lines of flow in the rear of the cylin ­ der, bounded by the contour DPC, and the lines of flow enclos­ ed within the contour D'A'B'HC. Now let us suppose the surface of the snow to be bounded by the line DPBB'QC. Then the snow which is drifted on the surface DP will be thrown in the direction PA, and the current carrying this snow will at the point A be divided in two. A por­ tion of the snow will be carried over the cylinder, while the rest will return to the point P, describing the path ABP, and ther& will be formed at the point P a snowdrift slanting towards the cylinder. In the rear of the cylinder there will be a region of stalled motion, but further away there will be generated a vortex whirling the snow and forming the mound Q.