In the case of streamline coordinates, in which the coordinate curves 

 ()) are parallel to the inviscid streamlines on the hull surface, U„ E and 



D 



U, = U. For this case, the momentum and displacement thicknesses of 

 definitions (4a-4f) then will be denoted by corresponding lower case Greek 

 letters and these definitions reduce to 



11 



"o 



J'^(-S) 



77 dA (5a) 



12 



-^0 



dA (5b) 



) = - r i^ 



^22 " "J iu 

 



^l = J (l- ^ ) dA (5e) 







dA (5c) 



2 



dA (5d) 



■It 



dA (5f) 



The quantity 6 is some overall nominal boundary layer thickness. The 

 relationships between the boundary layer thicknesses defined by Equations 

 (4a-4f) and those defined by Equations (5a-5f) will be needed later and 

 can readily be worked out. They are 



