CHARACTERISTICS OF SHIP BOUNDARY LAYERS 



L, Landweber 



University of Iowa 

 Iowa City^ Iowa 



I. INTRODUCTION 



When I accepted the invitation to lecture on ship boundary- 

 layers , my original plan was threefold: a) to review three-dimen- 

 sional boundary-layer theory, b) to discuss the few available appli- 

 cations of the theory to ship forms, and c) to present certain un- 

 published results on ship boundary layers that have been reported 

 in several theses at the University of Iowa. In the course of 

 attempting to "catch-up" on the literature on three-dimensional 

 boundary layers, so that I could pretend to be an authority on the 

 subject, I encountered so many excellent review articles, that it 

 became apparent that a review-of- reviews was hardly likely to 

 match the immortality achieved in its category by the "song-of- 

 songs, " Rather it seemed to be more useful and Interesting to 

 examine the validity and applicability to ship forms of the assump- 

 tions of existing methods for computing three -dimiensioncil boundary 

 layers, and to suggest and partly to implement certain approaches 

 which appear to be better suited to the ship problem. 



Some of the common assumptions of three-dimensioned 

 boundary -layer theory are the following: 



1. Assumption of small cross -flow -- that the direction of 

 flow within the boundary layer deviates by only a small angle from 

 the direction of the streamline at the outer edge of the boundary 

 layer. 



2. Assumption of methods of calculating two-dimensional 

 boundary layers for determining the velocity component parallel to 

 the outer streamline, even when the small cross-flow assumption is 

 avoided. 



3. The assumption of monotonic cross flow -- that as the 

 wall is approached from the outer streamline, and angle of deviation 

 of the boundary-layer streamlines increases monotonically up to a 

 certain value at a small distance from the wall, beyond which it 



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