NUMERICAL STABILITY OF THE 6-EQUATION, SINGLE-PRESSURE MODEL WITH VISCOUS TERMS

A standard model for describing time-dependent two-phase flows is the so-called six-equation or two-fluid model, where mass, energy, and mom entum equations are considered for each phase. It is well known that t he single-pressure form of this model can contain complex characterist ics and is therefore ill posed. This ill-posedness has been blamed for numerical instabilities that have at times been observed when finite difference solutions of these equations have been attempted. One metho d to render the characteristics real is to include viscous terms. The numerical implications of adding viscous terms to the six-equation mod el are considered, and the potential impact of these implications on t he stability of the finite difference solution is evaluated.