Acoustic scattering from flexible bodies with discontinuities using analytic/numerical matching

Analytical/numerical matching (ANM) is a hybrid scheme combining a low-resolution global numerical solution with a high-resolution local analytical solution to form a composite solution. ANM is applied to scattering from a fluid-loaded cylindrical membrane with a discontinuity, e.g., a point impedance. This coupled fluid/structural problem utilizes the addition and subtraction of canceling distributed forces at the discontinuity. The problem divides into one with the point force and distributed force in opposition, and another with only a distributed force. Conditions are imposed on the problem with the distributed force opposing the point force, leading to a structural response with only local motion and minimal radiation. This local problem can be solved analytically in simplified form. The remaining problem with only a distributed force is a low-resolution global numerical problem and can be solved efficiently. The local and global problems are dynamically coupled in the composite solution. The scattering problem revealed sensitivity to whether the discontinuity was a point force or a narrowly distributed force. This sensitivity is explained, and implications for accurate modeling of scattering from structures with discontinuities are discussed. Application of the method to multiple discontinuities and general geometry is described. [Work supported by ONR.]