Repairing near-singularity for dense EMC problems by adaptive basis techniques

Abstract

A standard boundary element method BEM discretisation for the electromagnetic compatibility EMC problem is analysed revealing the nearsingularity of the dense linear system for the lower frequency range Next a new basis transformation is presented that separates the dominating capacitive eects from the small but important inductive eects On this basis a sparse approximate inverse is constructed that is used not only as a preconditioner but also as a smoother for a multilevel preconditioner The number of matrixvector multiplications for the iterative solver is further reduced by reusing information Ritz vectors obtained from previous righthand side solves are injected into the search space of GMRESR thereby skipping the stagnation phase Reuse of information from the previous frequency computations has also been attempted but this is less eective Test results for the dierent methods are presented and compared