Laminar and turbulent flow about ship models

Total fluid resistance of a ship or ship model is commonly separated into viscous and dynamic components, corresponding to the tangential and normal components of the forces acting on the boundary surface.This separation has hitherto depended on calculated values of the viscous resistance based on experiments in which dynamic resistance was reduced to a minimum and assumed zero. Irregularities in viscous resistance are known to exist, however. There are two different regimes of flow in which tangential resistances have radically different values and it so happens that ordinary lengths and speeds of ship models bring them near, if not within the range of transition from one regime to the other. On the other hand, the dynamic resistance is still more obscurely related to the elements of geometrical form and speed than is the viscous resistance, and its systematic analysis continues to rest very largely on an empirical basis.The problem is to obtain accurate data as to these two quantities, such as will serve as an adequate basis for theoretical considerations, the only quantity amenable to experiment being their sum. Experimental methods have been refined considerably without bringing a definitive solution. A novel point of view is herewith presented which, it is hoped, may ultimately lead in the desired direction.