WAVE-INDUCED EDDIES AND "LIFT" FORCES 

 ON CIRCULAR CYLINDERS 



R. L. Wiegel and R. C. Delmonte 



University of California 

 Berkeley t California 3 U.S.A. 



ABSTRACT 



The frequency of eddies formed by and shed in the 

 lee of bluff bodies in steady flow is well known, and 

 to a lesser extent the associated "lift" forces have 

 been studied and are reasonably well understood. The 

 problem is more complicated in oscillatory flows 

 such as exists in water waves. Results of studies are 

 presented for the case of a vertical circular cylinder 

 which pierces the water surface. The value of the 

 Keulegan-Carpenter number (Nqjt) in correlating the 

 "lift" forces with the flow and cylinder parameters 

 is shown. For higher values of Nqj^ it is found that 

 the oscillatory flow tends to some extent to the stea- 

 dy state flow condition insofar as the "lift" forces 

 are concerned. However, owing to the fact that in os- 

 cillatory flow the"wake" becomes the upstream flow, 

 with eddies the same size as the cylinder, it is always 

 more complicated. The "lift" forces are irregular 

 for higher values of Nqj^ and should be described 

 by a distribution function ; examples of such func- 

 tions are given. 



INTRODUCTION 



The formation of eddies in the lee of a circular cylinder in 

 uniform steady flow normal to the axis of the cylinder has been studi 



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