Actuator line simulations of wind turbine wakes using the lattice Boltzmann method

Abstract

Abstract. The high computational demand of large-eddy simulations (LESs) remains the biggest obstacle for a wider applicability of the method in the field of wind energy. Recent progress of GPU-based (graphics processing unit) lattice Boltzmann frameworks provides significant performance gains alleviating such constraints. The presented work investigates the potential of LES of wind turbine wakes using the cumulant lattice Boltzmann method (CLBM). The wind turbine is represented by the actuator line model (ALM). 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 both laminar and turbulent inflow while a standard Smagorinsky sub-grid-scale model is employed in the two numerical approaches. The resulting wake characteristics are discussed in terms of the first- and second-order statistics as well the spectra of the turbulence kinetic energy. The near-wake characteristics in laminar inflow are shown to match closely with differences of less than 3 % in the wake deficit. Larger discrepancies are found in the far wake and relate to differences in the point of the laminar-turbulent transition of the wake. In line with other studies, these differences can be attributed to the different orders of accuracy of the two methods. Consistently better agreement is found in turbulent inflow due to the lower impact of the numerical scheme on the wake transition. In summary, the study outlines the feasibility of wind turbine simulations using the CLBM and further validates the presented set-up. Furthermore, it highlights the computational potential of GPU-based LBM implementations for wind energy applications. For the presented cases, near-real-time performance was achieved using a single, off-the-shelf GPU on a local workstation.

Evaluation of a lattice Boltzmann-based wind-turbine actuator line model against a Navier-Stokes approach

“…The Science of Making Torque from Wind (TORQUE 2022) Journal of Physics: Conference Series 2265 (2022) 022027 of 0.026s and an equivalent Mach number of M ≈ 0.13 for the LBM simulations. Asmuth et al [8] provide more details on the relation between Mach number and time step size in LBM wind turbine simulations. With this time step size, the blade elements do not cross more than one cell per time step, even at the tip.…”

“…Lattice Boltzmann-based approaches constitute a relevant alternative. There are no fundamental limitations for lattice Boltzmann method (LBM) to deal with atmospheric boundary layer (ABL) flows and wind turbine modelling capabilities with the same precision as Navier-Stokes (NS)-based approaches, as demonstrated in [6,7,8]. Furthermore, they exhibit much lower computational costs and are well-adapted to large-scale heterogeneous architectures.…”

On (non-)conservative body forces, vorticity generation and energy conversion in ideal flows

“…The disadvantage of this approach is that the force field needs to be known in advance of the analysis, which is not always the case. The first publication on this method is Sørensen & Shen (2002), whereas Asmuth, Olivares-Espinosa & Ivanell (2020) present a recent paper with an extensive bibliography. A first application in helicopter rotor analysis is found in Merabet & Laurendeau (2021).…”

Assessment of a heterogeneous computing CFD code in wind farm simulations

“…The exploration of heterogeneous computing in wind energy applications is incipient. Wind turbines simulations using the lattice Boltzmann method performed on GPU architecture are presented in [5]. The turbines rotor is represented using the Actuator Line Model [6].…”