Validation of a Large-Eddy Simulation Model to Simulate Flow in Pump Intakes of Realistic Geometry

Abstract

This paper describes efforts toward developing a reliable numerical model to predict pump intake flow and associated vortices. Numerical prediction of these flows characterized by the formation of unsteady (meandering) intermittent vortices and presence of massive separation is very challenging. Successful prediction of these phenomena and their effects on the mean flow fields requires numerical methods and turbulence models that can accurately capture the dynamics of the main coherent structures in these flows. In the present work, large-eddy simulation (LES) in conjunction with an accurate nondissipative nonhydrostatic Navier-Stokes massively parallel solver is used to predict the flow and vortical structures in a pressurized pump intake of complex geometry. The LES model is validated using particle image velocimetry data recently collected on a laboratory model of a realistic geometry pump intake. To better put in perspective the predictive performance of the LES model, results from steady simulations employing the shear stress transport (SST) Reynolds-averaged-Navier-Stokes (RANS) model are presented and compared with LES. It is shown that even if SST can fairly successfully capture the mean velocity distribution and mean vortical structures in some regions, overall LES can more accurately predict the mean flow and turbulence statistics compared to the steady SST model.