Comparison of the hyperbolic range of two-fluid models on two-phase gas -liquid flows Article in Press

In this paper, a numerical study is conducted in order to compare hyperbolic range of equations of isotherm two-fluid model governing on two-phase flow inside of pipe using conservative Shock capturing method. Differential equations of the two-fluid model are presented in two forms (i.e. form I and form II). In forms I and II, pressure correction terms are hydrodynamic and hydrostatic, respectively. In order to compare, the hyperbolic range of equations of two-fluid model is presented in two forms. One case (water Faucet Case) in the vertical configuration and two other cases (i.e. Large Relative Velocity Shock Tube Case and Toumi’s Shock Tube Case) in the horizontal configuration were used. The form I of two-fluid model had broader range of well-posing than form II of two-fluid model. The form I of two-fluid model has coefficient that proper selecting of this coefficient ensures hyperbolic roots of the characteristic equation, but in form II, roots of the characteristic equation did not have this capability.