Actuator Line – Interpolated bounce back approach in lattice Boltzmann method for wind turbine wake simulation

Wind turbine wakes affect the power output of a wind farm. Unsteady turbulent simulations are a powerful approach to predicting turbine wake and wake loss in wind farms. This study proposes a novel wind turbine wake simulation based on an actuator line (AL) model for the lattice Boltzmann method. The standard AL model represents only blades, and the absence of turbine structures, such as a nacelle and a tower, impairs the precision of wake calculations. In this study, the interpolated bounce-back method, a wall boundary condition commonly used in the lattice Boltzmann method, represents a nacelle and a tower and is combined with the AL model. The proposed hybrid approach is validated by a stand-alone turbine calculation of the NTNU “Blind Test” 1. A mesh convergence study is conducted with five simulation cases at varying grid spacing, confirming that the results converge with a grid spacing of D /96 for the velocity deficit and D /128 for the turbulent kinetic energy, where the rotor diameter is D . Comparisons of simulations with and without modeling the nacelle and tower show that including the full turbine structure improves wake prediction accuracy. The proposed method is further evaluated against eight previous CFD studies that used blade-resolved or actuator-line models. The lattice Boltzmann simulations with the proposed turbine model reproduce the experimental wake profiles of mean velocity deficit and turbulent kinetic energy with accuracy comparable to these studies, except under stall-mode operation.