Why the Coriolis force turns a wind farm wake clockwise in the Northern Hemisphere

Laan, P. van der; Sørensen, Niels N.

doi:10.5194/wes-2-285-2017

Cited by 50 publications

(33 citation statements)

References 20 publications

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“…One of the studies was performed with LES using a precursor simulation [16], this study indicated that a turn to the left dominated. These results gave a different conclusion than was found by Van der Laan [15]. Other studies found that the inclusion of the Coriolis force had some impact on the production for a full wake direction due to the turn of the wake [17].…”

Section: Introductionmentioning

confidence: 75%

“…Here Ω is the rotation of the Earth, φ is the latitude, u, w are the instantaneous local velocities and U, W are the mean values used in the FBL. The latitude 43.3 degrees is used in the studied case which corresponds to the Coriolis parameter f = 10 −4 1 s , also used by Van der Laan [15]).…”

Section: The Coriolis Correctionmentioning

confidence: 99%

“…It is natural to question whether the turn of the wake is more greatly impacted by the mean wind veer or change in Coriolis force due to variations in velocity. This question was studied by Van der Laan [15] using RANS with the conclusion that the main impact was from the wind veer due to the downward momentum transport in the wake. For the studied latitude (43.3 deg) in the northern hemisphere it led to a turn to the right of the wake region.…”

Section: Introductionmentioning

confidence: 99%

“…The study will also examine the impact of the wind veer and the change in Coriolis force in the wake region on the development of the wake. The setup regarding wind veer and latitude is similar to Van der Laan [15] to be able to compare his results using RANS by these using LES. Using the FBL technique and the Coriolis correction also allows for the study of the impact of wind veer and local impact of the Coriolis force in the wake region independently.…”

Section: Introductionmentioning

confidence: 99%

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Impact of Wind Veer and the Coriolis Force for an Idealized Farm to Farm Interaction Case

et al. 2019

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The impact of the Coriolis force on the long distance wake behind wind farms is investigated using Large Eddy Simulations (LES) combined with a Forced Boundary Layer (FBL) technique. When using the FBL technique any mean wind shear and turbulent fluctuations can be added with body forces. The wind shear can also include the mean wind veer due to the Coriolis force. The variation of the Coriolis force due to local deviations from the mean profile, e.g., from wakes, is not taken into account in the FBL. This can be corrected for with an extra source term in the equations, hereon defined as the Coriolis correction. For a row of 4 turbines it is shown that the inclusion of the wind veer turns the wake to the right, while including the Coriolis correction turns it to the left. When including both wind veer and Coriolis correction the impact of wind veer dominates. For an idealized farm to farm interaction case, two farms of 4 ∗ 4 turbines with 6 km in between, it can be seen that when including wind veer and the Coriolis correction a approximately 3% increase in the relative production for a full wake direction can be seen and only a slightly smaller increase can be seen when including only wind veer. The results indicate that FBL can be used for studies of long distance wakes without including a Coriolis correction but efforts need to be taken to use a wind shear with a correct mean wind veer.

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Section: Introductionmentioning

confidence: 75%

Section: The Coriolis Correctionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Impact of Wind Veer and the Coriolis Force for an Idealized Farm to Farm Interaction Case

et al. 2019

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“…Alya is an HPC code developed at the Barcelona Supercomputing Centre (BSC) to run large-scale applications. The code was recently tested on 100 000 processors and showed a parallel efficiency above 90 % (Vázquez et al, 2016). The k-ε model has been implemented and used in Alya for the present work.…”

Section: Model Descriptionmentioning

confidence: 99%

Micro-scale model comparison (benchmark) at the moderately complex forested site Ryningsnäs

et al. 2018

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This article describes a study in which modellers were challenged to compute the wind field at a forested site with moderately complex topography. The task was to model the wind field in stationary conditions with neutral stratification by using the wind velocity measured at 100 m at a metmast as the only reference. Detailed maps of terrain elevation and forest densities were provided as the only inputs, derived from airborne laser scans (ALSs) with a resolution of 10 m × 10 m covering an area of 50 km × 50 km, that closely match the actual forest and elevation of the site. The participants were free to apply their best practices for the simulation to decide the size of the domain, the value of the geostrophic wind, and every other modelling parameter. The comparison of the results with the measurements is shown for the vertical profiles of wind speed, shear, wind direction, and turbulent kinetic energy. The ALS-based data resulted in reasonable agreement of the wind profile and turbulence magnitude. The best performance was found to be that of large-eddy simulations using a very large domain. For the Reynolds-averaged Navier-Stokes type of models, the constants in the turbulence closure were shown to have a great influence on the yielded turbulence level, but were of much less importance for the wind speed profile. Of the variety of closure constants used by the participating modellers, the closure constants from Sogachev and Panferov (2006) proved to agree best with the measurements. Particularly the use of C µ ≈ 0.03 in the k-ε model obtained better agreement with turbulence level measurements. All except two participating models used the full detailed ground and forest information to model the forest, which is considered significant progress compared to previous conventional approaches. Overall, the article gives an overview of how well different types of models are able to capture the flow physics at a moderately complex forested site.Published by Copernicus Publications on behalf of the European Academy of Wind Energy e.V.

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Wake steering of multirotor wind turbines

et al. 2021

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In this paper, wake steering is applied to multirotor turbines to determine whether it has the potential to reduce wind plant wake losses. Through application of rotor yaw to multirotor turbines, a new degree of freedom is introduced to wind farm control such that wakes can be expanded, channelled or redirected to improve inflow conditions for downstream turbines. Five different yaw configurations are investigated (including a baseline case) by employing large‐eddy simulations (LES) to generate a detailed representation of the velocity field downwind of a multirotor wind turbine. Two lower‐fidelity models from single‐rotor yaw studies (curled‐wake model and analytical Gaussian wake model) are extended to the multirotor case, and their results are compared with the LES data. For each model, the wake is analysed primarily by examining wake cross‐sections at different downwind distances. Further quantitative analysis is carried out through characterisations of wake centroids and widths over a range of streamwise locations and through a brief analysis of power production. Most significantly, it is shown that rotor yaw can have a considerable impact on both the distribution and magnitude of the wake velocity deficit, leading to power gains for downstream turbines. The lower‐fidelity models show small deviation from the LES results for specific configurations; however, both are able to reasonably capture the wake trends over a large streamwise range.

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Why the Coriolis force turns a wind farm wake clockwise in the Northern Hemisphere

Cited by 50 publications

References 20 publications

Impact of Wind Veer and the Coriolis Force for an Idealized Farm to Farm Interaction Case

Impact of Wind Veer and the Coriolis Force for an Idealized Farm to Farm Interaction Case

Micro-scale model comparison (benchmark) at the moderately complex forested site Ryningsnäs

Wake steering of multirotor wind turbines

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