Superconvergence of mixed and nonconforming finite element methods
Yuwen Li
UCSD
Abstract:
In this talk, I will present superconvergence results of mixed and nonconforming
finite element methods on some mildly structured or structured grids. These
methods include Raviart-Thomas, Hellan-Herrmann-Johnson mixed methods,
and Courzeix-Raviart, Rannacher-Turek, Morley nonconforming methods. I
will prove some supercloseness estimates, that is, the canonical interpolant and
finite element solution are superclose in some norm. Then I will present several
recovery operators on irregular triangular grids by using the idea of local
least-squares fittings. Finally, I will show that the postprocessed finite element solution from those recovery operators superconverges to the exact solution in theory and experiments.