Mesh-adaptive simulations of horizontal-axis turbine arrays using the actuator line method

TL;DR

This paper introduces a mesh-adaptive actuator line model within a 3D fluid dynamics solver for efficient simulation of offshore wind farms, validated against wind tunnel data and applied to the Lillgrund wind farm.

Contribution

It presents a novel implementation of an adaptive mesh actuator line model in Fluidity, reducing computational costs for wind farm simulations.

Findings

Mesh adaptivity improves simulation efficiency.

Model accurately predicts wind tunnel test results.

Application to Lillgrund demonstrates practical benefits.

Abstract

Numerical models of the flow and wakes due to turbines operating within a real-scale offshore wind farm can lead to a prohibitively large computational cost, particularly when considering blade-resolved simulations. With the introduction of turbine parametrizations such as the actuator disk (AD) or the actuator line (AL) models, this problem has been partially addressed, yet the computational cost associated with these simulations remains high. In this work, we present an implementation and validation of an AL model within the mesh-adaptive three-dimensional fluid dynamics solver, Fluidity, under a unsteady Reynolds-averaged Navier-Stokes based turbulence modelling approach. A key feature of this implementation is the use of mesh optimization techniques, which allow for the automatic refinement or coarsening of the mesh locally according to the resolution needed by the fluid flow solver. The model is first validated against experimental data from wind tunnel tests. Finally, we demonstrate the benefits of mesh-adaptivity by considering flow past the Lillgrund offshore wind farm.