Salvesen 



DISCUSSION 



L. van Wijngaarden 

 Netherlands Ship Model Basin 

 Wageningen, The Netherlands 



Dr. Salvesen has calculated the drag by calculation of the wave energy. An- 

 other method to calculate the wave resistance is with help of the pressure dis- 

 tribution around the submerged body. Looking at the contours as given in Fig. 7, 

 which shows open bodies, the question occurred to me whether there is also a 

 vertical force on the body and of which order of magnitude. 



DISCUSSION 



W. D. Kim 



Davidson Laboratory 



Stevens Institute of Technology 



Hoboken, New Jersey 



In line with Tuck's earlier endeavor, given as Ref . 4, this paper points out 

 the nonlinearity effect from the free -surface condition which may partly be ac- 

 countable for the disagreement between the analytic and measured values of the 

 wave resistance of a body translating beneath the free surface. The author suc- 

 cessfully presented his contention through an extensive experiment in which the 

 addition of the nonlinear correction term clearly improves the prediction of the 

 wave profile. 



In Tuck's procedure, at outset, all the lengths of the problem were made 

 dimensionless by dividing with a typical length u^/g, which is a ratio of the 

 forward speed squared to the gravitational acceleration. Then the solution is 

 expressed in an asymptotic series with respect to the square of the dimension - 

 less radius 



g - 



a being the actual radius, as 







Therefore, it is essential to keep the perturbation parameter a small in order 

 that the series should converge. 



634 



