Characteristics and Stability Analyses for Two-Phase Flow Equation Systems with Viscous Terms

One-dimensional two-phase flow equations, describing mass and momentum equations for two phases, are used to analyze viscous term contributions to stability problems concerning two-phase flow equation systems. When viscous terms are taken into account, characteristics of the system become real. This paper shows that viscous terms stabilize disturbances, if the ratio of the system's dimension to the wavelength is sufficiently larger than the Reynolds numbers for the two phases. Some examples show that this result holds, when differential terms are added. An example of stable systems for any wavelength perturbations is given by adding a simple wall shear-like stress term. These results are obtained by the use of a linear stability analysis.