Charaateristios of Ship Boundary Layers 



DISCUSSION 



Dr. N. Hogben 

 National Physical Laboratory ^ Ship Division 

 Felthanij Middlesex^ England 



This paper performs a valuable service in laying the founda- 

 tions for a new method of calculating ship boundary layer properties 

 in terms of the vorticity field. A verdict on the merit of this ap- 

 proach must await the results of actual computations and comparison 

 with experiment. The purpose of this contribution Is to supplement 

 the review of experimented data given In the paper by drawing atten- 

 tion to work which I reported In 1964 (Ref. (*)). It comprised 

 boundary layer explorations covering the surface of a model with 

 mathematical form as defined by Wigley (Ref. (**)) having parabolic 

 waterllnes and section shapes. Measurements were made at 5 speeds 

 In the range 0. 16 < F^ < 0,32 and It Is of Interest that features 

 noted by Wleghardt as cited In the present paper were also observed. 

 In particular considerable stretching of the boundary layer below the 

 keel, likewise attributed to secondary flow effects, and bumps on the 

 velocity profiles attributed to trailing vortices, were found. 



REFERENCES 



(*) Hogben, N. , "Record of a boundary layer exploration on a 



mathematical ship model," Ship Division NPL Report No. 52, 

 July 1964. 



(**) Wigley, W. C. S. , "Calculated and measured wave resistance 



of a series of forms defined algebraically," Trans. R.I.N. A. 

 1942. 



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