An Improved Fringe-Region Technique for the Representation of Gravity Waves in Large Eddy Simulation with Application to Wind Farms

Lanzilao, Luca; Meyers, Johan

doi:10.1007/s10546-022-00772-z

Cited by 13 publications

(61 citation statements)

References 52 publications

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“…The governing equations (2.1)–(2.3) are solved using the SP-Wind solver, an in-house software developed over the past 15 years at KU Leuven (Meyers & Sagaut 2007; Calaf et al. 2010; Goit & Meyers 2015; Allaerts & Meyers 2017, 2018; Munters & Meyers 2018; Lanzilao & Meyers 2022, 2023 b ). The solver structure adopted here is mainly based on the version developed and used in Allaerts & Meyers (2017) and Lanzilao & Meyers (2022, 2023 b ).…”

Section: Methodsmentioning

confidence: 99%

“…2010; Goit & Meyers 2015; Allaerts & Meyers 2017, 2018; Munters & Meyers 2018; Lanzilao & Meyers 2022, 2023 b ). The solver structure adopted here is mainly based on the version developed and used in Allaerts & Meyers (2017) and Lanzilao & Meyers (2022, 2023 b ). The equations are advanced in time using a classic fourth-order Runge–Kutta scheme with a time step based on a Courant–Friedrichs–Lewy number of .…”

Section: Methodsmentioning

confidence: 99%

“…However, in case of stratified free atmospheres, a rigid-lid condition reflects back gravity waves triggered by the wind-farm drag force. To minimize gravity-wave reflection, we adopt a RDL in the upper part of the domain (Klemp & Lilly 1977; Durran & Klemp 1983; Allaerts & Meyers 2017; Lanzilao & Meyers 2023 b ). This body force dissipates the upward energy transported by gravity waves before it reaches the top of the domain and it reads as where , and with the geostrophic wind angle.…”

Section: Methodsmentioning

confidence: 99%

“…Second, the presence of gravity waves requires the use of appropriate methods for inflow and outflow conditions together with non-reflective upper boundary conditions. Only very recently, a first approach was proposed, based on a wave-free fringe-region technique (Lanzilao & Meyers 2023 b ), that does not excite spurious waves at the inlet and outlet of the simulation domain, while still allowing for a turbulent inflow in LES. In the current work we use this approach to set-up a large simulation study that focuses on the influence of thermal stratification above the ABL on wind-farm performance and wind-farm blockage.…”

Section: Introductionmentioning

confidence: 99%

“…Various more recent studies have further investigated this behaviour both using LES (Wu & Porté-Agel 2017; Allaerts et al. 2018; Lanzilao & Meyers 2022, 2023 b ; Maas 2022, 2023; Maas & Raasch 2022) and much faster linearized wind-farm flow models (Allaerts & Meyers 2019; Devesse et al. 2022; Smith 2022, 2023).…”

Section: Introductionmentioning

confidence: 99%

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A parametric large-eddy simulation study of wind-farm blockage and gravity waves in conventionally neutral boundary layers

Lanzilao,

Meyers

2024

J. Fluid Mech.

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We present a suite of large-eddy simulations (LES) of a wind farm operating in conventionally neutral boundary layers. A fixed 1.6 GW wind farm is considered for 40 different atmospheric stratification conditions to investigate effects on wind-farm efficiency and blockage, as well as related gravity-wave excitation. A tuned Rayleigh damping layer and a wave-free fringe-region method are used to avoid spurious excitation of gravity waves, and a domain-size study is included to evaluate and minimize effects of artificial domain blockage. A fully neutral reference case is also considered, to distinguish between a case with hydrodynamic blockage only, and cases that include hydrostatic blockage induced by the air column above the boundary layer and the excitation of gravity waves therein. We discuss in detail the dependence of gravity-wave excitation, flow fields and wind-farm blockage on capping-inversion height, strength and free-atmosphere lapse rate. In all cases, an unfavourable pressure gradient is present in front of the farm, and a favourable pressure gradient in the farm, with hydrostatic contributions arising from gravity waves at least an order of magnitude larger than hydrodynamic effects. Using respectively non-local and wake efficiencies $\eta _{nl}$ and $\eta _{w}$ , we observe a strong negative correlation between the unfavourable upstream pressure rise and $\eta _{nl}$ , and a strong positive correlation between the favourable pressure drop in the farm and $\eta _{w}$ . Using a simplified linear gravity-wave model, we formulate a simple scaling for the ratio $(1-\eta _{nl})/\eta _{w}$ , which matches reasonably well with the LES results.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A parametric large-eddy simulation study of wind-farm blockage and gravity waves in conventionally neutral boundary layers

Lanzilao,

Meyers

2024

J. Fluid Mech.

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Stable Boundary Layers with Subsidence: Scaling and Similarity of the Steady State

Bon,

Cal,

Meyers

2024

Boundary-Layer Meteorol

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A fast-running physics-based wake model for a semi-infinite wind farm

Bastankhah,

Mohammadi,

Lees

et al. 2024

J. Fluid Mech.

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This paper presents a new generation of fast-running physics-based models to predict the wake of a semi-infinite wind farm, extending infinitely in the lateral direction but with finite size in the streamwise direction. The assumption of a semi-infinite wind farm enables concurrent solving of the laterally averaged momentum equations in both streamwise and spanwise directions. The developed model captures important physical phenomena such as vertical top-down transport of energy into the farm, variable wake recovery rate due to the farm-generated turbulence and also wake deflection due to turbine yaw misalignment and Coriolis force. Of special note is the model's capability to predict and shed light on the counteracting effect of Coriolis force causing wake deflections in both positive and negative directions. Moreover, the impact of wind farm layout configuration on the flow distribution is modelled through a parameter called the local deficit coefficient. Model predictions were validated against large-eddy simulations extending up to 45 km downstream of wind farms. Detailed analyses were performed to study the impacts of various factors such as incoming turbulence, wind farm size, inter-turbine spacing and wind farm layout on the farm wake.

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An Improved Fringe-Region Technique for the Representation of Gravity Waves in Large Eddy Simulation with Application to Wind Farms

Cited by 13 publications

References 52 publications

A parametric large-eddy simulation study of wind-farm blockage and gravity waves in conventionally neutral boundary layers

A parametric large-eddy simulation study of wind-farm blockage and gravity waves in conventionally neutral boundary layers

Stable Boundary Layers with Subsidence: Scaling and Similarity of the Steady State

A fast-running physics-based wake model for a semi-infinite wind farm

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