[en] The transient two-phase flow analyzer : MINCS is developed to provide a computational tool for evaluation of various two-phase flow models including the constitutive relations which are given by users, according to the type of field equations specified. A new systematic numerical technique is developed for solving the field equations. This technique is featured by (i) a degeneration from a basic two-fluid nonequilibrium (2V2T) model to simpler models such as the drift flux model on the basis of the finite difference equations for 2V2T model and (ii) a fully-implicit scheme in the time integration of all flow variables including coefficients calculated by empirical correlations. The first feature provides that the same solution method is used for all models, and thus numerical errors such as truncation errors do not depend on the model used. This feature makes the code powerful in evaluating constitutive relations through comparisons among the various models and in extending the applicability of existing correlations to new situations. (author)