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(Block 20 continued) 



obtained by dividing computed potential jump by body length, 

 assuming that the body is slender or flat in the direction of 

 motion. The potential jump is expressed explicitly in terms of 

 the effective volume, i.e., the sum of the displaced volume and 

 added mass/density of the submerged body, and the depth Froude 

 number, if a free surface is present. As a test of the present speed 

 correction formula, two cases are considered: (1) the Wigley para- 

 bolic ship model, tested in both a small and a large towing tank, 

 (2) a body of revolution (prolate spheroid) tested in a 

 circular wind tunnel. In each case the mean-speed increment 

 averaged over the entire body surface is computed by a three- 

 dimensional, finite-element method applicable to free-surface 

 flow problems. These are shown to be in good agreement with 

 those obtained by the approximate speed correction formula. 

 At high values of Froude numbers, the main difference in the 

 total resistance coefficients measured in the two towing tanks 

 by Tamura is due primarily to difference in model wave resistance 

 computed for the two tanks by a full-fledged, three-dimensional, 

 finite-element method. Results are also compared to those ob- 

 tained by using the speed correction formula of Lock and Johansen. 

 The present formula renders a better approximation than that of 

 Lock and Johansen when the cross sectional area of a flow tunnel 

 is not much larger than the maximum cross section area of the 

 body . 



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