Three‐Dimensional Air Flow: The Vortex Street Theory of Karman and Rubach is here Extended to Three Dimensional Considerations

AS far as the author is aware, no attempt has yet been made, either on the experimental or on the theoretical side, to extend to three dimensions the conceptions regarding the formation of a vortex street in the wake of a body, as developed by Karman and Rubach for two dimensions. The problem is complicated by the fact that owing to experimental difficulties there is an almost complete absence of direct visual evidence regarding the nature of the flow in the wake of a three‐dimensional body. This makes it extremely difficult to construct, in imagination, the possible vortex configuration that might originate. It should be understood, therefore, at this stage, that until such direct evidence is available, the suggestions put forward here are to be regarded as merely of a tentative nature, but this has not prevented mathematical investigation on the basis of these suggestions from proceeding.