Andreas

March 3, 2004 07:21 
Problem Buoyancy Term
I am computing natural convection applying the Boussinesq approximation. So, I am solving the NavierStokes equations with a buoyant term and a convectiondiffusion equation for the temperature. If the environmental temperature, that is considered in the buoyant term (TTinf) of the momentum equation, is not zero, the nonlinear solver diverges, otherwise everything works fine. Mathemetically spoken, the system of coupled nonlinear PDEs is not invariant against a shift in temperature. Analytically every constant added to the temperature should cancel, if respected in the bouyant term. I should mention that I use a stabilized NavierStokes discretization. Has someone an explanation for this phenomena?
