Three-dimensional/one-dimensional seamlessly coupled simulation of cavitating flow in reciprocating positive displacement pumps and their piping

A novel three-dimensional/one-dimensional (3D/1D) coupled simulation method is applied to study cavitation dynamics in a simplex plunger positive displacement pump. The compressible 3D unsteady Reynolds-averaged Navier–Stokes equations are solved by a finite volume method, using deforming meshes and a two-way coupled fluid–structure interaction approach for modeling fluid-actuated valve dynamics. The method incorporates a mass transfer cavitation model and accounts for non-dissolved air. Structural compliance is approximated by an enhanced fluid compressibility. The 3D method is seamlessly coupled with a 1D method of characteristics for the suction-side piping, using a finite difference flow solver. Spurious reflections at the 3D/1D coupling interface are minimized by equalizing the discretization errors of the 3D and the 1D solver. A partially reflective boundary treatment controls wave reflections at the suction side boundary of the 1D domain. Experimental validation is carried out using time-resolved pressure and flow rate data for both single-phase and cavitating flow condition. The method captures essential cavitation phenomena such as water hammer and the interaction of void structures. Remaining deviations from data observed during the initial valve opening phase are attributed to the omission of adhesion effects. We highlight that incorporating non-dissolved air into the cavitation model and using the 1D method for piping flow simulation, rather than conventional boundary conditions in the 3D solver, significantly improves the accuracy in reproducing the measured pressure characteristics.