EFFICIENT FIELD POINT EVALUATION BY COMBINED DIRECT AND HYBRID BOUNDARY-ELEMENT METHODS

A new procedure for calculating held points with the boundary element method (BEM) is outlined. In the conventional BEM (CBEM) field points are computed as post-professing by recurrently solving the boundary in tegral equation with known boundary data for every field point of inte rest. This procedure is very time-consuming. On the other hand, newly developed hybrid boundary element formulations (HBEMs) based on variat ional principles compute field points from the known boundary solution by simply transforming it to the domain using fundamental solutions a s field approximation. The advantage of the HBEM is that the related s ystem matrices are symmetric by construction but the computational eff ort to obtain the boundary solution is higher than in CBEMs. Thus, if symmetry of the system matrices has no priority, it is advantageous to compute the boundary solution with the CBEM and the field point solut ion with the HBEM. The additional implementation effort is relatively low, since only one extra matrix has to be computed, which is sparse a nd has analytical entries. (C) 1998 Elsevier Science Ltd. All rights r eserved.