Based on acoustic radiation modes, the surface contribution method has been developed to predict the surface contributions to the radiated sound power from a vibrating structure. In this work, the surface contribution method is used to identify the sound field on a vibrating structure submerged in a heavy fluid. It was recently found that surface contribution method was not able to predict the ...

In this paper we study the distributed and boundary optimal control of the Stokes equations in presence of pointwise control constraints. The analysis of the problems involve existence results, as well as necessary conditions and optimality systems. A primal-dual active set strategy is studied for the numerical solution of the problems. For the distributed case, global and local convergence res...

The purpose of this paper is to present an adaptive FEM-BEM coupling method that is valid for both twoand three-dimensional elasto-plastic analyses. The method takes care of the evolution of the elastic and plastic regions. It eliminates the cumbersome of a trial and error process in the identification of the FEM and BEM sub-domains in the standard FEM-BEM coupling approaches. The method estima...

An analytical method for evaluating pole-residues in spectral method of moments (MoM) formulations is presented. Spectral integral formulations for periodic structures involve the inverse of the MoM matrix, which exhibits a periodic set of pole singularities, corresponding to the zeros of the matrix’s determinant. So far, these singularities have not been extracted and the corresponding pole-re...

In this paper, a mortar element method is presented for coupling natural boundary element method and finite element method for the Dirichlet exterior problem. Optimal error estimate is obtained and some numerical results are reported.

H-Matrix LU-decomposition based preconditioners for BEM

The numerical solution of the Helmholtz equation with nonlocal radiation boundary conditions is considered. We model sound wave propagation in a multilayered piecewise homogeneous medium. A fourth-order accurate collocated, boundary element method is used, where the solution inside the domain is computed through a representation integral. The method is shown to have the expected fourth-order co...

Many boundary integral equations for exterior boundary value problems for the Helmholtz equation suffer from a notorious instability for wave numbers related to interior resonances. The so-called combined field integral equations are not affected. However, if the boundary is not smooth, the traditional combined field integral equations for the exterior Dirichlet problem do not give rise to an L...

The need for numerical methods in studying electromagnetic scattering from rough surfaces is well established. The most commonly used numerical method is the surface integral equation method and its solution by the method of moments (MoM). Conventional implementation of MoM requires O(N^3) operations, where N is the number of surface unknowns. When N is large, as frequently encountered in study...

An adaptive nite element–boundary element algorithm is proposed to compute an approximate solution of a given boundary value problem. The convergence in H ( ) is controlled by a boundary element based a-posteriori error estimator from which an adaptive re nement strategy is derived. Corresponding error estimates are given based on appropriate boundary element error estimates in negative Sobolev...