© 2001 by Institute of Mathematics and its Applications
Boundary integral methods for singularly perturbed boundary value problems
1 Department of Mathematical Sciences, University of Bath, Bath BA2 7AY, UK, e-mail: stephen.langdon{at}durham.ac.uk e-mail: igg{at}maths.bath.ac.uk
In this paper we consider boundary integral methods applied to boundary value problems for the positive definite Helmholtz-type problem
U +
2U = 0 in a bounded or unbounded domain, with the parameter
real and possibly large. Applications arise in the implementation of spacetime boundary integral methods for the heat equation, where
is proportional to 1/(
t), and
t is the time step. The corresponding layer potentials arising from this problem depend nonlinearly on the parameter
and have kernels which become highly peaked as
, causing standard discretization schemes to fail. We propose a new collocation method with a robust convergence rate as
. Numerical experiments on a model problem verify the theoretical results.
Key Words: singular perturbation, boundary integral method, Helmholtz equation, heat equation, collocation, trigonometric polynomial
Received 11 August 1998. Accepted 12 December 1999.