Numerical quadratures for near-singular and near-hypersingular integrals in boundary element methods
This work provides a practical numerical tool for engineers and scientists using boundary element methods, though it is an incremental extension of prior work on singular integrals.
The paper develops a method for deriving Gaussian quadrature rules that integrate near-singular and near-hypersingular integrals common in boundary element methods, achieving errors comparable to machine precision on standard reference integrals.
A method of deriving quadrature rules has been developed which gives nodes and weights for a Gaussian-type rule which integrates functions of the form: f(x,y,t) = a(x,y,t)/((x-t)^2+y^2) + b(x,y,t)/([(x-t)^2+y^2]^{1/2}) + c(x,y,t)\log[(x-t)^2+y^2]^{1/2} + d(x,y,t), without having to explicitly analyze the singularities of $f(x,y,t)$ or separate it into its components. The method extends previous work on a similar technique for the evaluation of Cauchy principal value or Hadamard finite part integrals, in the case when $y\equiv0$. The method is tested by evaluating standard reference integrals and its error is found to be comparable to machine precision in the best case.