Numerical model for calculation of hydraulic transients with two-phase flow and fluid-structure interaction

Abstract

This paper presents a model for the solution of hydraulic transients with two-phase flow and fluid-structure interaction. Mathematical and numerical solutions are proposed and analyzed for the proper capture of the physical phenomena associated with fluid compressibility and fluid celerity, which are variable in two-phase fluids, together with the disturbances generated by fluid-structure interaction. The proposed solution for the model considers the simultaneous action of these phenomena. The developed numerical model is based on the solution of a mathematical model formed by a system of four partial differential equations, in which the necessary adaptations are integrated into fluid-structural equations and in the nonlinear mathematical coefficients for the solution of the compressible and two-phase flow in question. The classical formulation is selected for the implementation of friction between fluid and pipe in the model. For the solution, the method of characteristics and finite difference are applied, with subsequent numerical integration. The validation of the results is carried out based on comparisons with experimental and analytical data.