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In all of these studies, either a uniform mesh or a block-mesh strategy was employed within the presented simulations. Hence, the actuator disk model was used in previous 1- 5 to model the wake field and predict the power output of operating offshore wind farms (eg, Lillgrund and Horns Rev) while others 6- 8 undertook AL simulations to solve for the wake field as well as to obtain statistics for blade loads.
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These two factors have rendered the use of TPMs a computationally affordable alternative approach for the modelling of large-scale wind farms. Second, the introduction of the momentum source to represent the motion of the blades circumvents the need to use either a rotating or an overlapping mesh strategy to capture the motion of the turbine rotor. First, by using TPMs, the number of degrees of freedom needed by the fluid solver is significantly reduced since the boundary layer of the individual blades is no longer required to be resolved. Turbine parametrization models (TPMs) such as the actuator line model (ALM) and the actuator disk model (ADM) exhibit a large number of advantages compared to blade-resolved simulations, both in terms of their respective computational efficiency but also as far as their implementation within a CFD solver is concerned. Finally, we demonstrate the benefits of mesh-adaptivity by considering flow past the Lillgrund offshore wind farm. The model is first validated against experimental data from wind tunnel tests. 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. 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. 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.
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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.