Sound scattering by cylinders of noncircular cross section

Abstract

This thesis investigates a new method for predicting the farfield scattered pressure of a plane wave due to an infinite cylinder of noncircular cross section. Both impenetrable and penetrable :fluid boundary condi tions will be treated for several types of cross sections and for a large frequency range. This new method requires the conformal mapping of both the exterior and interior of a closed surface to a semi-infinite strip. Numerically efficient algorithms wi ll be presented for both of these cases. A new method for satisfying the boundary conditions will be developed, as well as an efficient algorithm for generating the required modal functions on the boundary. Numerical results are presented for cross sections in the shape of an ellipse, square, and three leaf clover. In all cases, the results compare extremely well with exact or high frequency asymptotic results.