Direct vs. Indirect Boundary Element Methods

Abstract

Direct and indirect boundary-element formulations are compared in the context of calculating the fluid mass matrix for two-dimensional flow of an ideal fluid external to cylindrical surfaces. The accuracy of calculated eigenvalues for the associated fluidboundary eigenproblem is used to assess performance. It is found that the indirect method is generally more accurate, which is attributed to the fact that boundary-element discretization directly constrains only the source field in the indirect formulation, whereas it directly constrains both the pressure and velocity fields in the direct formulation.