Truncated Method of Characteristics for Quasi-Two-Dimensional Water Hammer Model

Abstract

A new and efficient variant of the method of characteristics for solving the quasi-two-dimensional water hammer model is proposed. The method requires the fully implicit discretization scheme for radial velocity, to eliminate this velocity from the equations for axial velocity and piezometric head. As the radial velocity is typically outside the scope of interest, the computation time is reduced by omitting its calculation. The proposed method is compared with an existing method by means of two water hammer benchmark tests. The results of the two methods practically match, but the proposed method requires approximately 50% less CPU time for the laminar flow test, and 30% for the turbulent one. In addition, the numerical accuracy of four implicit interpolation schemes is compared for the case of laminar flow. The obtained results suggest that the required fully implicit discretization is not a significant limitation of the proposed method. The new method offers high numerical efficiency, while retaining all merits of the existing method.