A two-grid finite element method for semilinear PDEs with
interface
Yunrong Zhu
UCSD
Abstract:
In this talk, we consider solving semilinear PDEs with
discontinuous diffusion coefficients by a two-grid algorithm. The
algorithm consists of a coarse solver on the original nonlinear
problem, and a single linear Newton update. Under the assumption that
the nonlinear function is monotone, we derive the a priori $L^{\infty}$
bounds of the continuous solution, and $L^{\infty}$ bounds on the
discrete solutions with additional angle condition on the
triangulation. With the help of these a priori $L^{\infty}$ bounds, we
derive quasi-optimal error estimate. We also derive the $L^2$ error
estimate via duality argument. Finally, we give the error estimate on
the numerical solution generated by the two-grid algorithm. Numerical
results justify our theoretical conclusions.