Development and Verification of a Semi-implicit Three-Field Pilot Code

The thermal/hydraulic behavior of a multiphase flow is predicted by solving the related governing equations. The equations are devised based on the mass, momentum, and energy conservation laws and physical models defining the thermal and mechanical interactions between the phases involved. A great deal of effort has been paid, during the past two or three decades, to solve the equations in an efficient and stable manner. A reliable methodology to obtain the solution of the equation set is essential, especially in a nuclear thermal/ hydraulic safety analysis where the consequences of the various hypothetical incidents are required to be within a predefined range of acceptance. In this study, a semi-implicit solver is developed for a one-dimensional channel flow as three-fields. The three field modeling of water is similar to a method employed in codes such as COBRA. The three fields are comprised of a gas, continuous liquid and entrained liquid field. All the three fields are allowed to have their own velocities. The continuous liquid and the entrained liquid are, however, assumed to be in a ermal equilibrium