Abstract
The solution of the Stokes problem in a polygonal domain of
R
2
is in general not regular. But it can be written as the sum of a regular part and a linear combination of singular functions. We propose a numerical analysis of the Strang and Fix algorithm by mortar spectral element methods which leads to an Inf-Sup condition on the pressure in a non-conforming decomposition. We prove optimal error estimates for the velocity and the pressure.