RETRAN Dynamic Slip Model

A time-dependent equation for the slip velocity in a two-phase flow condition has been incorporated into the RETRAN-02 computer code. This model addition was undertaken to remove a limitation in RETRAN-01 associated with the homogeneous equilibrium mixture model The dynamic slip equation was derived from a set of two-fluid conservation equations. The slip model and the flow-regime-dependent constitutive equations are used in the RETRAN steady-state initialization solution as well as for transient analyses. Comparisons of RETRAN calculations with steady-state and transient data indicate the slip model results in a better analysis of two-phase flow behavior than does the homogeneous equilibrium mixture model