Investigation of Turbulence Modeling for Point-Absorber-Type Wave Energy Converters

Abstract

Reviewing the literature of CFD-based numerical wave tanks for wave energy applications, it can be observed that different flow conditions and different turbulence models are applied during numerical wave energy converter (WEC) experiments. No single turbulence model can be identified as an `industry standard’ for WEC modeling. The complexity of the flow field around a WEC, together with the strong dependency of turbulence effects on the shape, operational conditions, and external forces, hampers the formulation of such an `industry standard’. Furthermore, the conceptually different flow characteristics (i.e., oscillating, free surface flows), compared to the design cases of most turbulence models (i.e., continuous single-phase flow), can be identified as a source for the potential lack of accuracy of turbulence models for WEC applications. This communication performs a first step towards analyzing the accuracy and necessity of modeling turbulence effects, by means of turbulence models, within CFD-based NWTs for WEC applications. To that end, the influence of turbulence models and, in addition, the influence of the initial turbulence intensity is investigated based on different wave–structure interaction cases considering two separately validated WEC models. The results highlight the complexity of such a `turbulence analysis’ and the study suggests specific future work to get a better understanding of the model requirements for the flow field around WECs.

Keywords

• wave energy
• CFD
• RANS
• turbulence modeling