Mor-ij Inui and Kajitani 



new distribution be close to that yielded by the experiment. They show 

 that the agreement between the wave amplitude functions calculated 

 from the new distribution and those derived from a longitudinal cut 

 remains unsufficiently good. They conclude that researches are to be 

 pursued in one or two other directions. I just heard from Professor 

 Inui that one obtains a very good agreement between the two kinds of 

 wave amplitude functions if one adds to the effect of the sources that 

 of a line integral which I had considered in a paper [3J submitted, for 

 discussion, in June 1971, to my Colleagues of the I. T. T. C. Resist- 

 ance Committee. 



I consider as an interesting attempt the introduction of the 

 wave profile on the hull into the calculation of the singularity distri- 

 bution. One of the reasons why this does not provide a sufficiently 

 good agreement with experiment may be the effect of viscosity and 

 turbulence. The wave theory for inviscid fluid does not apply inside 

 the boundary layer and wake. The longitudinal cut method does not 

 give rise to this objection. 



What is to be concluded from the effect of the line integral ? 

 In the last months, Professor Landweber [4j has gone further that I 

 did a year and half ago in the afore -mentioned paper on the Neumann- 

 Kelvin problem. He has shown that, if the hull is represented by a 

 source distribution the line integral canbe transformed into a source dis- 

 tribution over the hull. Therefore one can solve the Neumann-Kelvin pro- 

 blem by using only a source distribution over the hull. But this requires 

 the treatment of an integral equation with a kernel depending on the 

 speed of the ship. However, if the first approximation is that obtained 

 from the Zero Froude number condition, it can be shown that this ap- 

 proximation is certainly inaccurate when the Froude number decreases, 

 and that the line integral expressed in term of that distribution should 

 greatly improve the calculated wave resistance [5J. Hence, more de- 

 tailed information on the procedure used by the authors for determin- 

 ing both "the wave -analyzed source distribution" and the line integral 

 associated with it would be very much appreciated. 



I would like to add that I am not convinced that wave breaking 

 is responsible for the discrepancy between calculation and experiment, 

 for the M-21 form is thin. 



Much more important is undoubtedly the effect of the boundary 

 layer and wake, not only because it entails a sensible loss of total 

 head, but also because the boundary condition on the hull is altered. 

 For this reason, I suggest that (it would be desirable that) the exper- 

 iments of the authors be completed by a wake survey. 



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