Codice 41/2011 Titolo Numerical Approximation of Large Contrast Problems with the Unfitted Nitsche Method Data 2011-11-23 Autore/i Burman, E.; Zunino, P.; Link Download full text Pubblicato to appear as a chapter in: Frontiers in Numerical Analysis - Durham 2010, LNCSE, Springer, 2012 Abstract These notes are concerned with the numerical treatment of the coupling between second order elliptic problems that feature large contrast between their characteristic coefficients. In particular, we study the application of Nitsche s method to set up a robust approximation of interface conditions in the framework of the finite element method. The notes are subdivided in three parts. Firstly, we review the weak enforcement of Dirichlet boundary conditions with particular attention to Nitsche s method and we discuss the extension of such technique to the coupling of Poisson equations. Secondly, we review the application of Nitsche s method to large contrast problems, discretised on computational meshes that capture the interface of discontinuity between coefficients. Finally, we extend the previous schemes to the case of unfitted meshes, which occurs when the computational mesh does not conform with the interface between subproblems.