Large Eddy Simulation of 3 X 3 wind turbine array using Actuator Line model with spectral elements

Abstract

The current paper aims at performing large eddy simulation in spectral element framework of a 3 × 3 wind turbine array in atmospheric boundary layer (ABL) with near wall modelling for rough-wall geometry at very high Reynolds number. The wind turbine rotors have been represented by state of the art reduced order Actuator Line (AL) model analogous to immersed boundary methodology which is computationally more efficient than resolving turbine blade boundary layer. The inflow condition is fed from an ABL simulation using spectral interpolation method. We present an analysis of multiscale turbulent dynamics and power generated by a 3 × 3 wind turbine array from the statistical moments and validate the result from experimental observations.

Dynamics of Large Scale Turbulence in Finite-sized Wind Farm Canopy using Proper Orthogonal Decomposition and a Novel Fourier-POD Framework

“…The database for the finite sized wind farm have been obtained from spectral element simulations in LES carried out in our previous work [5,31,32]. In particular, we use the open-source exponentially accurate spectral element code Nek5000 [33,34] for setting up the LES simulation.…”

“…The domain consists of a 3 × 3 wind turbine array (WT) in a realistic inflow-outflow [31,35] setup, and hence the turbine array layout is finite-sized. The inter-turbine streamwise and spanwise distances are 7d and 3d respectively.…”

“…We further illustrate the schematic of the three-dimensional layout in Figure 1a and supported by a typical snapshot of fluctuating streamwise velocity at hub-height ( Figure 1b), where the multiscale feature of ABL-turbulence around the rotor regions are evident. Table 1 shows the specification of the domain size of the wind turbine array as well as the precursor neutral ABL which is concurrently simulated to generate inflow conditions [31,32]. Additionally, the grid counts and the average normalized grid sizes for the farm layout as well as neutral ABL ( turbulent scales fed to the inflow) can be found in Table 2.…”

“…From table 1 it is apparent that the precursor neutral ABL has a much uniform distribution of grids compared to the wind turbine (WT) domain. This is primarily because of the fact that the WT domain grids were build on the top of ABL domain, with grid refinements around the turbine rotors (∼ 30 gridpoints per actuator line blade) for capturing the wake turbulence accurately [31,35,43,50]. The number of snapshots obtained from the simulations is 3285, which are spaced 1/5T e apart (T e = 15πd/U ∞ is the flow-through time).…”

Regularization modelling for large‐eddy simulation in wall‐bounded turbulence: An explicit filtering‐based approach

“…9,10 The application of weak formulation using spectral element methods (SEMs) to LES is relatively less explored, although several works in this domain published since the last decade must be noted. [11][12][13][14][15][16][17][18] A traditional approach to LES is to generate the differential equations governing the spatio-temporal evolution of large-scale structures, which can be obtained from the Navier-Stokes equations by applying a low-pass filter. The filtering of nonlinear convective product term does not commute with the convection of filtered quantities, which gives rise to an additional term in filtered Navier-Stokes equations called subgrid-scale (SGS) or subfilter-scale term requiring closure.…”