186 



0.15 Y 



ACKNOWLEDGMENT 



FIGURE 20. Wake distribution at (1/8)L AFT from A. P. 

 (MS-02) . 



be because in the present calculations the potential 

 components are determined with no attention to dis- 

 placement effects. 



Figure 20 shows the calculated wake distribution 

 compared with measured. They do not always produce 

 quantitative agreement with each other, but compli- 

 mental uses of the present calculations with model- 

 wake survey may offer a useful method for the 

 prediction of full scale wake characteristics. 



It is expected that much further improvement can 

 be attained by taking into account the D- and E- 

 regions. 



CONCLUSION 



The flow characteristics of boundary layers and 

 wakes of ship-like bodies are discussed. The fol- 

 lowing remarks can be mentioned as conclusions; 

 (i) The pressure-constant assumption of boundary 

 layer is a good approximation except near the 

 ship stern or bilge keel where there is a 

 small radius of curvature. The pressure does 

 not recover near the stern because of the dis- 

 placement effects of the boundary layer. 

 (ii) Most commonly used semi-empirical equations 

 for velocity profiles, skin friction, and 

 entrainment can be safely employed in case of 

 ship-like bodies, but the functional expres- 

 sion for crossflow in boundary layer has a 

 certain limit for large or reverse crossflows. 

 (iii) The integral method of boundary layer calcu- 

 lation may be carried out more effectively by 

 a hybrid use of integral and finite-difference 

 methods, 

 (iv) The three-dimensional boundary layer separa- 

 tion is closely related to pressure distribu- 

 tion on the hull surface. Its initiation is 

 referred to the occurrence of large crossflow. 

 (v) The eddy viscosity coefficient is about 300- 

 times the molecular one, in the ship's wake, 

 (vi) The separated flow region has sub-regions 



which have different characteristics and no 

 single approximate equation of Navier-Stokes 

 equation is valid uniformly for all regions, 

 (vii) The local asymptotic expansion method is 



promising for the separated flow. Further 

 experimental investigations as to turbulence 

 are necessary. 



The assistance of graduate students of the Faculty 

 of Engineering of Hiroshima University, who partici- 

 pated in carrying out experiments and numerical 

 calculations, is cordially appreciated. 



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