Accession Number : AD0690919

Title :   DIFFRACTION AND PROPAGATION OF A PLANE SHOCK WAVE AT A FREE SURFACE.

Descriptive Note : Technical rept.,

Corporate Author : CALIFORNIA UNIV LOS ANGELES SCHOOL OF ENGINEERING AND APPLIED SCIENCE

Personal Author(s) : Chen,Michael Hsiang-Ten ; Collins,Richard

Report Date : JUN 1969

Pagination or Media Count : 80

Abstract : The propagation of shock waves in stratified media finds important application in the oceans and upper atmosphere. Such shocks or blast waves may be formed by supersonically traveling vehicles or as a direct consequence of strong explosions. This work is divided into two parts. The first part examines the motion of an initially uniform shock front traveling parallel to the y-axis. At time t=0, the shock crosses the free interface (y=0) separating a homogeneous fluid in the upper half-plane (x>0, y>0) from a different homogeneous fluid in the lower half-plane (x>0, y<0). The subsequent motion of the shock front is determined as it propagates through two fluids. The interaction obtained depends on the initial speed of the shock relative to the sound speeds or more generally on the acoustic impedances in each of the two media. The second part deals with the motion of the shock itself which may be approximated by Whitham's method, using a coordinate system consisting of a network formed by successive shock wave positions on one hand, and the orthogonal trajectory to the shock on the other. The diffracted shock is found to be surprisingly uniform, except in the vicinity of the free surface and the undisturbed shock, where it undergoes large changes in curvature. The work provides the possibility of extension to shock propagation in general stratified media. (Author)

Descriptors :   (*SHOCK WAVES, PROPAGATION), DIFFRACTION, UPPER ATMOSPHERE, OCEANOGRAPHY, INTERFACES, FLOW FIELDS, SURFACE PROPERTIES, EXPLOSION EFFECTS, THESES

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE