Rate form of the equation of state for thermalhydraulic systems: numerical considerations

In conjunction with the usual rate forms of the conservation equations, the time derivative form of the equation of state is investigated from a numerical consideration point of view. First, the derivation of the rate form of the equation of state is presented. Systematic comparison between the new method and the traditional iterative method is made by applying the method to a simple flow problem. The comparison is then extended to a practical engineering problem requiring accurate prediction of pressure. The rate method is found to be more advantageous in many aspects. It is more intuitive for system analysis, more appropriate for eigenvalue extraction, as well as easier to program and to implement. Numerically, the rate method is found to be more efficient and accurate than the traditional method.