Robins-Magnus Effect: A Continuing Saga.

Abstract: The experimental observation by Robins1, that a projectile spinning about its axis of travel experiences a transverse force (lift), was refuted by Euler2 purely as a contradiction to expected symmetry of fluid flow. This, undoubtedly had taken away the precedence of finding this effect by Robins and subsequently the same was credited to Magnus3, which is a testimony of “belief ” overtaking physical observation. In the last century Prandtl 4 looked at this problem once again and came up with an upper limit on lift that a spinning cylinder will experience. This is now considered a fundamental tenet in explaining aerodynamic phenomenon of lift generation. However, over the last two decades evidences are accumulating via experimental 6,5 and numerical investigations 8,7 that a new temporal instability affects this flow at high rotation rates, negating the above mentioned upper limit. In this note, we trace the origin of this particular effect to its present day status with respect to flow past a rotating cylinder