TECHNIQUE OF DETERMINING THE VISCOUS DRAG OF A SHIP MODEL BY MEANS OF A WAKE SURVEY.
Abstract
The purposes of the present work were to evaluate the validity and accuracy of the various viscous drag formulas, to investigate the influence of turbulence in the wake, and to study the feasi bility of a practical, routine technique for making viscous-drag measurements. An exact formula for the viscous drag was derived in a recent paper, in which two new approximations and evaluation of their errors by means of a mathematical model were also presented. The momentum-control surface selected in this case is a rectangular box moving with the ship model at a constant speed U in the negative x-direction. This control surface consists of two vertical transverse sections, S sub O, far ahead of the model, and S, at a moderate distance behind it, over which the measurements are to be taken; the free surface, through which there is no momentum flux; and bottom and sides, which are situated at great distance from the model. It was assumed that the flow is irrotational outside the wake and that this external potential flow could be continued analytically into the wake by a suit able distribution of sources and sinks within the ship model and the wake. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1963
- Accession Number
- AD0418436
Entities
People
- Jin Wu
Organizations
- University of Iowa