PREDICTING THE EFFECTS OF SURFACE SUCTION AND BLOWING ON THE STROUHAL FREQUENCIES IN VORTEX SHEDDING

Through the use of scaling arguments, a simple model describing the boundary layer behavior during vortex shedding is proposed. The main focus of the model, which is based on the assumption that the viscous diffusion length is directly proportional to the boundary layer thickness, is set towards predicting the salient features, but not the details, of the periodic flow. Promising results have been achieved upon applying the model to the classical problem of vortex shedding over a solid circular cylinder. It is noted, however, that there is a need for further scrutiny in terms of a detailed comparison of the predicted results with existing numerical data. The model has also been applied towards investigating the behavior of the vortex shedding or Strouhal frequencies as influenced by boundary layer suction and injection (blowing) occurring normal to the stream. Among the interesting findings dealing with this part of the study, a critical Reynolds number is predicted which acts as the transition from one limiting frequency behavior to another.