30th International Conference on Parallel Computational Fluid Dynamics Parallel CFD2018 LBM-BASED LARGE-EDDY SIMULATION OF WIND TURBINE ROTOR WAKE AERODYNAMICS RALF DEITERDING * , CHRISTOS GKOUDESNES * AND ADEN COX * * Aerodynamics and Flight Mechanics Research Group University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK e-mail: r.deiterding@soton.ac.uk, web page: http://rdeiterding.website Key words: Large eddy simulation, lattice Boltzmann method, wind turbine aerody- namics, parallel block-structured adaptive mesh refinement Abstract. Lattice Boltzmann methods are a particularly suitable approach for simulating unsteady wake aerodynamics with high resolution. In this work, we focus on parallel large- eddy simulations of wind turbine wakes imposed by actuator disk and actuator line models. The verification of the turbulence model by a forced isotropic turbulence test case is also discussed. High fidelity is achieved by patch-based structured mesh adaptation provided by our AMROC framework. 1 INTRODUCTION The rotor of an operating horizontal axis wind turbine creates a large-scale turbulent rotating wake structure. While it is undisputed that upstream wakes have a major in- fluence on the power output of downwind turbines, the understanding of wind turbine wake creation and interaction is still quite poor. High fidelity large eddy simulation (LES) is a promising avenue to improve on this. While the majority of available compu- tational fluid dynamics methods for wind engineering approximate the incompressible or weakly compressible Navier-Stokes equations, we use utilize here the lattice Boltzmann method (LBM) that is explicit in time and easily parallelizable. Being a type of Carte- sian immersed boundary method, the LBM is also well suited for modeling fluid-structure interaction. While in previous work [1, 2], we had focused on modeling wind turbines as resolved moving embedded surface mesh structures, we concentrate here on approaches representing rotors as momentum forcing terms. 2 METHODS The simplified Boltzmann equation with additional force term reads ∂ t f + u ·∇f = ω(f eq − f )+ F . Introducing the partial density distribution functions f α (x, t), we turn the latter into the discrete lattice Boltzmann equation f α (x + e α Δt, t +Δt)= f α (x,t)+ ω L Δt (f eq α (x,t) − f α (x,t)) + ΔtF α , (1) which assumes that a breakdown of F into a suitable set of F α is considered as part of the particle collision process. Note, however, that also different approaches have been proposed for including force terms into the LBM. 1