A universal Strouhal law
Abstract
A universal Strouhal number law, based on an fd/U value of 0.16, is defined and applied to several phenomena involving an oscillation in a restrained fluid body induced by an external free flow, the velocity of the free flow, and the dimension of the body. The specific mechanical and kinetic energy of the oscillator is formulated for the case when the Strouhal number is 0.16, and local oscillations following the law are demonstrated to have a wavelength of 2(pi)d when convected by the flow. The formulation is applied to autorotating wings, jets, wakes, shock waves, axisymmetric vortex breakdown, fixed cavitation, surface waves, and internal waves. The results show that the law is useful for predicting the oscillation frequency of a fluid when the fluid body thickness and the outer flow speed are known quantities, thereby aiding in characterizing critical conditions of flowinduced structural vibrations.
 Publication:

Journal of Engineering and Mechanics
 Pub Date:
 June 1983
 Bibcode:
 1983JEngM.109..718L
 Keywords:

 Flow Stability;
 Free Flow;
 Oscillating Flow;
 Strouhal Number;
 Structural Vibration;
 Computational Fluid Dynamics;
 Flow Velocity;
 Kinetic Energy;
 Traveling Waves;
 Vortex Shedding;
 Wave Propagation;
 Fluid Mechanics and Heat Transfer