Accession Number : AD0746191

Title :   The Small Froude Number Paradoxes and Wave Resistance at Low Speeds.

Descriptive Note : Technical rept.,

Corporate Author : HYDRONAUTICS INC LAUREL MD

Personal Author(s) : Dagan,Gedeon

Report Date : JUN 1972

Pagination or Media Count : 65

Abstract : Two basic asymptotic expansions of the equations of two-dimensional free-surface gravity flow past a body are first discussed: (i) the thin body, and (ii) the naive small Froude number expansions. It is shown that different solutions are obtained for small Froude number and thin body from (i) and (ii) (the first paradox), because (ii) is not uniform in the downstream region of the flow domain, where waves are concentrated. Moreover, the thin body expansion, which leads at first order to the usual linearized wavemaking approximation, is not uniform as the Froude number tends to zero (the second paradox). By using the exact solution of a model problem, linearized free-surface conditions leading to uniform small Froude number solutions have been derived. (Author)

Descriptors :   (*TWO DIMENSIONAL FLOW, EQUATIONS OF MOTION), ANALYTIC FUNCTIONS, INTEGRAL EQUATIONS, PARTIAL DIFFERENTIAL EQUATIONS, APPROXIMATION(MATHEMATICS), HYDRODYNAMICS, THREE DIMENSIONAL FLOW, SHIPS, ASYMPTOTIC SERIES

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE