Accession Number : AD0465132
Title : ON THE SURFACE WAVE PATTERN OF SUBMERGED BODIES STARTED FROM REST
Descriptive Note : Technical rept.
Corporate Author : HYDRONAUTICS INC LAUREL MD
Personal Author(s) : Hsu, C C
Report Date : Apr 1965
Pagination or Media Count : 30
Abstract : The initial surface wave pattern due to a submerged body started from rest with uniform speed in a perfect fluid is studied. The mean surface elevations may, in general, be separated into three parts: (1) A steady local disturbance which travels both upstream and downstream and diminishes as the distance from the body increases, (2) a group of steady regular waves which travel downstream from the origin x=0 to x=1/2 Ut with group velocity 1/2 U, and (3) a time-dependent cylindrical disturbance which travels both upstream and downstream and diminishes rapidly as time increases. For sufficiently long time t, the general expression for the unsteady disturbance can be obtained by the method of stationary phase. It is found that for a given finite value of t, the effect of the unsteady disturbance becomes more serious as the downstream distance from the body increases. It is also shown that the initial unsteady effect is, at lower Froude numbers, more persistent and therefore takes a longer time to subside. A comparison of the predicted centerline wave profile due to a submerged 9 feet long, 7 to 1, Rankine ovoid started from rest with DTMB data has been made; the results are in very good agreement.
Descriptors : *WATER WAVES , *INTERNAL WAVES , *UNDERWATER OBJECTS , VELOCITY , SURFACE PROPERTIES , WAKE , PARTIAL DIFFERENTIAL EQUATIONS , FLUID DYNAMICS , HYDRODYNAMICS , UNDERWATER TRAJECTORIES
Subject Categories : Fluid Mechanics
Distribution Statement : APPROVED FOR PUBLIC RELEASE