DIFFRACTION OF PULSES BY OBSTACLES OF ARBITRARY SHAPE WITH A ROBIN BOUNDARY CONDITION. PART B. SEMI-FREE CASE.
STATE UNIV OF NEW YORK BUFFALO DIV OF INTERDISCIPLINARY STUDIES AND RESEARCH
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The velocity field resulting from the diffraction of a plane acoustic wave by a scattering obstacle of arbitrary shape with a Robin boundary condition, is found as the solution to an integro-differential equation. Numerical values are found for the velocity on the surface of a long cylinder of square cross section struck longitudinally by a plane pulse through an approximation of the integral by finite summations over specified steps in space and time. Comparison with exact solutions available for certain regions of space-time indicate good agreement. The solution for small values of K does not differ greatly from that for K 0 indicating that the free boundary condition is a reasonable approximation for many physical problems. Values of K up to 1.0 in appropriate nondimensional form seem to give most reasonable rsults in terms of velocity for K 10 a formulation in terms of pressure seems more appropriate and for values 1 K 10 either form will do. Author