Thank you all
1.) I am trying to solve lid driven cavity problem for an incompressible Stokes and Navier Stokes equations using general "Mixed" finite element method. dirchlet boundary conditions are specified everywhere on the boundary.
when i try to solve these system of equations, my matrix showing is that it is singular. My doubt is whether it is necessary to specify pressure value at some point ? otherwise how to impose the constraint "average pressure over the domain is zero" ? in FEM.
2.) I am trying to simulate incompressible flow over a cylinder using mixed finite element method. dirchlet boundary conditions are specified at inlet,top, bottom, on circle and do nothing on outlet.
Is it necessary to give pressure value at some point ?