CALCULATION OF INCOMPRESSIBLE VISCOUS FLOWS BY AN UNCONDITIONALLY STABLE PROJECTION FEM

This paper investigates the numerical performance of a finite element implementation of a new incremental fractional-step method to compute steady and unsteady incompressible viscous flows under general boundar y conditions and using unstructured meshes. A variational framework is adopted which accommodates two different spaces for representing and approximating the velocity fields calculated respectively in the visco us and inviscid phases of the method, but which leads to a very simple numerical scheme in terms of only one discrete velocity field. An unc onditionally stable semi-implicit approximation of the nonlinear term is used to eliminate any time-step restriction, as far as the numerica l stability is concerned. Numerical results for five test problems in two dimensions are reported to illustrate the flexibility of the propo sed method. (C) 1997 Academic Press.