||March 3, 2004 07:21
Problem Buoyancy Term
I am computing natural convection applying the Boussinesq approximation. So, I am solving the Navier-Stokes equations with a buoyant term and a convection-diffusion equation for the temperature. If the environmental temperature, that is considered in the buoyant term (T-Tinf) 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 Navier-Stokes discretization. Has someone an explanation for this phenomena?