Comparison of a mid-fidelity free vortex wake method to a high-fidelity actuator line model large eddy simulation for wind turbine wake simulations

Abstract

The need for mid-fidelity wind turbine simulations is increasing due to their balance of accuracy and computational efficiency. A common form of mid-fidelity code is the free wake vortex method (FVWM), but these are known to inaccurately represent the far-wake depending on their implementation. Herein, we compare CACTUS, a FVWM code, to Nalu-Wind, an actuator line model large eddy simulation (ALM-LES) code with particular focus on the far wake. Specifically, we compare one CACTUS simulation, which necessarily has steady and uniform inflow, to three Nalu-Wind simulations using a steady and uniform inflow, a low turbulence inflow, and a high turbulence inflow. The comparison reveals interesting parallels between CACTUS and all Nalu-Wind cases, but ultimately demonstrates that CACTUS is not an appropriate tool for the simulation of the far-wake of a wind turbine.