Studies on Wake Vortices (ⅲ): Experimental Investigation of the Wake Behind a Sphere at Low Reynolds Numbers

By Sadatoshi TANEDAWakes produced by a sphere moving in a tank of water were photo• graphically investigated at Reynolds numbers from 5 to 300.Main results obtained are as follows.1.The critical Reynolds number at which the permanent vortex-ring begins to form in the rear of a sphere is about 24. 2. The size of vortex-ring is nearly proportional to the logarithm of the Reynolds number.3, The .wake behind a sphere begins to oscillate at the rear of the perma• nent vortex-ring when Reynolds number of about 130 is reached.