Near-wake analysis of actuator line method immersed in turbulent flow using large-eddy simulations

Nathan, Jörn; Masson, Christian; Dufresne, Louis

doi:10.5194/wes-3-905-2018

Cited by 16 publications

(7 citation statements)

References 28 publications

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“…These are found in all presented cases, yet generally slightly smaller in the NS solutions. This signature at f B was recently described by Nathan et al (2018) but using twice as many grid points per diameter when compared to the highest resolution shown here. It can thus be appreciated that this transient feature of the ALM remains traceable down to resolutions of ∆x = D/16.…”

Section: Wake Characteristicssupporting

confidence: 76%

Actuator Line Simulations of Wind Turbine Wakes Using the Lattice Boltzmann Method

Asmuth¹,

Olivares-Espinosa²,

Ivanell³

2019

Preprint

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Abstract. The presented work investigates the potential of large-eddy simulations (LES) of wind turbine wakes using the cumulant lattice Boltzmann method (CLBM). The wind turbine is represented by the actuator line model (ALM) that is implemented in a GPU-accelerated (Graphics Processing Unit) lattice Boltzmann framework. 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 a uniform laminar inflow while a standard Smagorinsky sub-grid scale model is employed in both numerical approaches. The comparison shows a good agreement in terms of the blade loads and near-wake characteristics. The main differences are found in the point of laminar-turbulent transition of the wake and the resulting far-wake. In line with other studies these differences can be attributed to the different orders of accuracy of the two methods. In a second part the possibilities of implicit LES with the CLBM are investigated using a limiter applied to the third-order cumulants in the scheme's collision operator. The study shows that the limiter generally ensures numerical stability. Nevertheless, a universal tuning approach for the limiter appears to be required, especially for perturbation-sensitive transition studies. In summary, the range of discussed cases outline the general feasibility of wind turbine simulations using the CLBM. In addition, it highlights the potential of GPU-accelerated LBM implementations to significantly speed up LES in the field of wind energy.

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Section: Wake Characteristicssupporting

confidence: 76%

Actuator Line Simulations of Wind Turbine Wakes Using the Lattice Boltzmann Method

Asmuth¹,

Olivares-Espinosa²,

Ivanell³

2019

Preprint

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show abstract

“…Examples thereof range from the standard Smagorinsky model (Hou et al, 1996;Krafczyk et al, 2003) to more advanced models like the wall-adapting local eddy-viscosity model (WALE; Weickert et al, 2010), the shear-improved Smagorinsky model (SISM; Jafari and Mohammad, 2011), and dynamic Smagorinsky approaches (Premnath et al, 2009b). Others, on the other hand, suggested LB-specific methods based on the approximate deconvolution of the LBE itself (Sagaut, 2010;Malaspinas and Sagaut, 2011;Nathen et al, 2018).…”

Section: Sub-grid-scale Modelling In the Lbmmentioning

confidence: 99%

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

2020

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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.

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“…The first ADM combining BE theory with computational fluid dynamics (CFD) is from Sørensen and Myken (1992) and Sørensen and Kock (1995). This model was later extended to the ALM and used in combination with LES (Sørensen and Shen, 2002;Nathan et al, 2018;Sørensen et al, 2015;Nathan et al, 2017;Asmuth et al, 2020). Later developments combining LES with the ADM are, for example, from Porté-Agel et al (2011) and van der Laan et al (2015).…”

Section: Airfoil-based Forcesmentioning

confidence: 99%

Actuator line model using simplified force calculation methods

et al. 2023

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Abstract. To simulate transient wind turbine wake interaction problems using limited wind turbine data, two new variants of the actuator line technique are proposed in which the rotor blade forces are computed locally using generic load data. The proposed models, which are extensions of the actuator disk force models proposed by Navarro Diaz et al. (2019a) and Sørensen et al. (2020), only demand thrust and power coefficients and the tip speed ratio as input parameters. In the paper the analogy between the actuator disk model (ADM) and the actuator line model (ALM) is shown, and from this a simple methodology to implement local forces in the ALM without the need for knowledge of blade geometry and local airfoil data is derived. Two simplified variants of ALMs are proposed, an analytical one based on Sørensen et al. (2020) and a numerical one based on Navarro Diaz et al. (2019a). The proposed models are compared to the ADM using analogous data, as well as to the classical ALM based on blade element theory, which provides more detailed force distributions by using airfoil data. To evaluate the local force calculation, the analysis of a partial-wake interaction case between two wind turbines is carried out for a uniform laminar inflow and for a turbulent neutral atmospheric boundary layer inflow. The computations are performed using the large eddy simulation facility in Open Source Field Operation and Manipulation (OpenFOAM), including Simulator for Wind Farm Applications (SOWFA) libraries and the reference National Renewable Energy Laboratory (NREL) 5 MW wind turbine as the test case. In the single-turbine case, computed normal and tangential force distributions along the blade showed a very good agreement between the employed models. The two new ALMs exhibited the same distribution as the ALM based on geometry and airfoil data, with minor differences due to the particular tip correction needed in the ALM. For the challenging partially impacted wake case, both the analytical and the numerical approaches manage to correctly capture the force distribution at the different regions of the rotor area, with, however, a consistent overestimation of the normal force outside the wake and an underestimation inside the wake. The analytical approach shows a slightly better performance in wake impact cases compared to the numerical one. As expected, the ALMs gave a much more detailed prediction of the higher-frequency power output fluctuations than the ADM. These promising findings open the possibility to simulate commercial wind farms in transient inflows using the ALM without having to get access to actual wind turbine and airfoil data, which in most cases are restricted due to confidentiality.

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Near-wake analysis of actuator line method immersed in turbulent flow using large-eddy simulations

Cited by 16 publications

References 28 publications

Actuator Line Simulations of Wind Turbine Wakes Using the Lattice Boltzmann Method

Actuator Line Simulations of Wind Turbine Wakes Using the Lattice Boltzmann Method

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

Actuator line model using simplified force calculation methods

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