Accession Number : AD0895052

Title :   Boundary Conditions at Free Surfaces and Fixed Walls.

Descriptive Note : Technical memo.,

Corporate Author : HYDROFOIL CORP ANNAPOLIS MD

Personal Author(s) : Vavra, M. H.

Report Date : 12 MAR 1951

Pagination or Media Count : 9

Abstract : There are shown three typical cases of boundary conditions at an interface. From a theoretical point of view the bi-plane method, that has been used to evaluate surface effects of hydrofoils, is only applicable if the densities of the fluids, meeting at the free surface, were of equal magnitude. Generally, the boundary conditions for hydrofoil phenomena can only be satisfied by an equation. However, for cases where the Froude number is very large this condition reduces to the boundary condition that makes possible the application of the bi-plane method. It is difficult to evaluate the differences that occur if the bi-plane method is used instead of the correct formulation, or to stipulate the minimum Froude number that permits to use the bi-plane method. In cases where the bound vortex drag constitutes a considerable portion of the total drag it is necessary to apply the correct formulation of the boundary condition.

Descriptors :   (*HYDROFOILS, BOUNDARY LAYER), SURFACES, FLUID FLOW, INTERFACES, VORTICES, DRAG, MATHEMATICAL MODELS, WALLS, HYDRODYNAMIC CONFIGURATIONS, PLANING SURFACES, TWO DIMENSIONAL FLOW.

Subject Categories : Marine Engineering
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE