A residual-potential boundary for time-dependent, infinite-domain problems in computational acoustics.

A theoretically exact computational boundary is introduced, that is based on modal residual potentials for the spherical geometry. The boundary produces a set of first-order, uncoupled ordinary differential equations for nodal boundary responses, and a set of uncoupled time-stepping equations for modal boundary responses. The two sets are coupled through nodal-modal transformation based on the orthogonal surface functions for the spherical boundary. Numerical results generated with the boundary are presented for a step-wave-excited, elastic, spherical shell submerged in an infinite acoustic medium. Extension of the method to other separable geometries for partial differential equations defined in unbounded domains is mentioned.