Numerical Predictions of Hydrokinetic Turbine Wake and Free Surface Signatures

Elfajri, O., & Bhushan, S. (2018). Numerical Predictions of Hydrokinetic Turbine Wake and Free Surface Signatures. he Mississippi Academy of Science 82nd Annual Meeting. University of Southern Mississippi.

Abstract

Hydrokinetic turbine is more complex than wind turbine study, its complexity lies in their interaction with the air-water interface, which can affect both wake recovery and result in signatures on the surface. Computational Fluid Dynamics (CFD) has proven to be a well-established method for wake evaluation in terms of cost and time compared to experiments. Previous numerical studies have focused on the wake recovery of an isolated HKT in single phase flow using ANSYS/Fluent. Herein, we will extend the study and focus on the free surface effect on the HKT wake and reciprocally the effect of the wake on the free surface. The results and details of the wake recovery will then be validated using experimental data from literature and previous single-phase Fluent simulations. The study demonstrates that OpenFOAM results were in good agreement with Fluent results. The thick boundary layer accelerates the flow and creates a blockage effect. Hexahedral meshes perform better than mixed cells grids by displaying well-defined vortices structures. The final paper will include more comprehensive results of the single phase with DES and LES results and two phases with the free surface effect.