Analysis of a non-symmetric coupling of Interior Penalty DG and BEM

Norbert Heuer and Francisco-Javier Sayas
Math. Comp. 84 (292), 581-598, 2015.

We analyze a non-symmetric coupling of interior penalty discontinuous Galerkin and boundary element methods in two and three dimensions. Main results are discrete coercivity of the method, and thus unique solvability, and quasi-optimal convergence. The proof of coercivity is based on a localized variant of the variational technique from [F.-J. Sayas, The validity of Johnson-Nédeléc's BEM-FEM coupling on polygonal interfaces, SIAM J. Numer. Anal., 47(5):3451-3463, 2009]. This localization gives rise to terms which a re carefully analyzed in fractional order Sobolev spaces, and by using scaling arguments for rigid transformations. Numerical evidence of the proven convergence properties has been published previously.