The general characteristic of two-dimensional floe behind a cylinder of any cross section are well known, and for the purpose of mathematical investigation it has been assumed that at an appreciable distance from the obstacle, the vortices in the wake assume a regular formation known as the “unsymmetrical double row” or “Karmanstrasse” -in which each vortex is opposites the mid point of the interval between consecutive vortices on the other row. The form of the wake seen experimentally justifies, in some measures, the adoption of this assumption. The theoretical investigation of the stability of such double row in a channel* brought out some unexpected results and of it was thought that an experiments investigation would throw some light on the subject. Quite a number of experiments have, from time to time, investigated the two-dimensional flow behind a cylinder, but there has been no systematic attempt to find the effect of the channel walls on the dimensions of the karman street. Further, the existence of some possible simple functional relation between the various dimensions has almost always been masked by the choice of an obstacle of complicated cross section, the most usual obstacle being one of aerofoil section. It was therefore thought advisable to use some cylinder of circular section so as to avoid, to some degree, the complications introduced by the shape of the obstacle. No theoretical explanation of the result is attempted, but the figures derived from the investigations are submitted as information on various features of the flow. The actual experiments were conducted by Herr m. Schwabe at the Kaiser Wilhelm-Institute für Strömungsforschung, at Göttingen, and it was his patient investigation that was made it possible to obtain a complete description of the vortex motion. Figs. 1-6 of this paper, and part of the tables, were completed by him at Göttingen. I feel extremely grateful to him for leaving undertaken the investigations and for having carried them out in such an efficient manner. My thanks are also due to Prof. L. Prandtl, Director of the Kaiser Wilhelm-Institut, for having allowed the experiments to be conducted in his laboratory and for having put at my disposal the apparatus and facilities which made the experiments possible. In the last instance, however, my thanks are due to the Department of Scientific and Industrial Research whose Senior Research Award enabled me to finance the investigation.
A Generalized Numerical Method for Bluff Body and Stalling Aerofoil Flow