Actuator Line Simulations of Wind Turbine Wakes Using the Lattice Boltzmann Method

Abstract

Abstract. The presented work investigates the potential of large-eddy simulations (LES) of wind turbine wakes using the cumulant lattice Boltzmann method (CLBM). The wind turbine is represented by the actuator line model (ALM) that is implemented in a GPU-accelerated (Graphics Processing Unit) lattice Boltzmann framework. The implementation is validated and discussed by means of a code-to-code comparison to an established finite-volume Navier-Stokes solver. To this end, the ALM is subjected to a uniform laminar inflow while a standard Smagorinsky sub-grid scale model is employed in both numerical approaches. The comparison shows a good agreement in terms of the blade loads and near-wake characteristics. The main differences are found in the point of laminar-turbulent transition of the wake and the resulting far-wake. In line with other studies these differences can be attributed to the different orders of accuracy of the two methods. In a second part the possibilities of implicit LES with the CLBM are investigated using a limiter applied to the third-order cumulants in the scheme's collision operator. The study shows that the limiter generally ensures numerical stability. Nevertheless, a universal tuning approach for the limiter appears to be required, especially for perturbation-sensitive transition studies. In summary, the range of discussed cases outline the general feasibility of wind turbine simulations using the CLBM. In addition, it highlights the potential of GPU-accelerated LBM implementations to significantly speed up LES in the field of wind energy.