Fourth-order differential equations play an important role in many applications science and engineering. In this paper, we present a three-field mixed finite-element formulation for fourth-order problems, with focus on the effective treatment of different boundary conditions that arise naturally variational formulation. Our is based introducing gradient solution as explicit variable, constraine...

In this paper, we propose an extended mixed finite element method for elliptic interface problems. By adding some stabilization terms, present a approximation form based on Brezzi-Douglas-Marini space and the piecewise constant function space, show that discrete inf-sup is independent of how intersects triangulation. Furthermore, derive optimal convergence holds location relative to mesh. Final...