Development of three-dimensional analysis code for two-phase flow using two-fluid model

A numerical calculation method for two-phase flow behavior using a three-dimensional, two-fluid model has been developed. In this model, the control volume formulation and non-staggered mesh scheme were employed instead of the finite difference method and staggered mesh scheme which have been commonly used in numerical analyses for two-phase flow. Moreover, the porous medium approach was implemented for modeling of internal structures in the flow path in order to evaluate their effects with comparatively fewer meshes. Since the control volume formulation is based on the space integrated amount of the conserved quantities, the present method can satisfy the accuracy requirements of conservation equations based on the two-fluid model. In the non-staggered mesh scheme, pressure, density and void fraction are defined at the same location as phase velocities are defined. Calculation accuracy of this scheme can be higher than that of staggered mesh scheme because that does not require the interpolation of the void fraction between neighboring nodes at the location where phase velocities are defined. The present method has been applied to the analyses of two-dimensional two-phase flow behavior in a piping elbow and in a three-dimensional sudden expanded flow area, in order to confirm the calculation capability of phase separation and void fraction distribution caused by the density difference. (author)