plates. Their work is a good reference because it shows a systematic correlation 

 of the variation in the coefficients of drag (C^) and mass (Cj^.j). The following 

 items are described: analysis of forces on objects at rest in a moving fluid, with 

 the special case of a cylinder in a sinusoidal fluid velocity; the experimental 

 wave tank and force dynamometer; data reduction; flow patterns which resulted; and 

 possible reasons for the variation in coefficients due to vortex formation. The 

 results of primary interest were for cylinders: 



1. The average values of Cq and Cy during a wave cycle were correlated 



with the period pai'ameter" 



vhere U is the amplitude of the sinusoidal fluid 



velocity. T = period, d = cylinder diameter. No correlation was found with the 

 Reynolds number. The results are plotted in figures 11 and 12. 



DIAMETER (INCHES): 3 

 CORRES. SYMBOL: o 



c, 



D 



U^T/d 



Figure 11. Variation of drag coefficient of cylinders. 



25 



