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Wind Energy Science
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Wind farms operate in the atmospheric boundary layer and their performance is strongly dependent on the atmospheric conditions. We propose a simple model of the atmospheric boundary layer that can be used as an inflow model for wind farm simulations for isolating a number of atmospheric effects, namely, the change of wind direction with height and atmospheric boundary layer depth. In addition, the simple model is shown to be consistent with two similarity theories.
Wind farms operate in the atmospheric boundary layer and their performance is strongly dependent...
Preprints
https://doi.org/10.5194/wes-2020-130
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/wes-2020-130
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
08 Jan 2021
08 Jan 2021
Review status: a revised version of this preprint is currently under review for the journal WES.
A pressure-driven atmospheric boundary layer model satisfying Rossby- and Reynolds number similarity
- DTU Wind Energy, Technical University of Denmark, Risø Campus, Frederiksborgvej 399, 4000 Roskilde, Denmark
- DTU Wind Energy, Technical University of Denmark, Risø Campus, Frederiksborgvej 399, 4000 Roskilde, Denmark
Abstract. Idealized models of the atmospheric boundary layer (ABL) can be used to leverage understanding of the interaction between the ABL and wind farms, towards improvement of wind farm flow modelling. We propose a pressure-driven one-dimensional ABL model without wind veer, which can be used as an inflow model for three-dimensional wind farm simulations for isolating the effects of wind veer and ABL depth. The model is derived from the horizontal momentum equations, and follows both Rossby- and Reynolds number similarity; use of such similarity reduces computation time and allows rational comparison between different conditions. The proposed ABL model compares well with solutions of the mean momentum equations that include wind veer, if the forcing variable is employed as a free parameter.
How to cite. van der Laan, M. P., Kelly, M., and Baungaard, M.: A pressure-driven atmospheric boundary layer model satisfying Rossby- and Reynolds number similarity, Wind Energ. Sci. Discuss. [preprint], https://doi.org/10.5194/wes-2020-130, in review, 2021.
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Maarten Paul van der Laan et al.
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RC1: 'Elegant ABL model for efficient computation of homogeneous inflow conditions', Javier Sanz Rodrigo, 26 Jan 2021
Elegant formulation of an ABL model with numerical properties to allow efficient computation of wind conditions by dropping dependencies on the wind sheer. The model is motivated by previous papers from the authors grounded on the concept of Re and Ro similarity and provide a practical approach to the parameterization of the model using pre-computed ABL simulations. I have only minor remarks and suggestions that can help in the understanding the derivation of the model. In particular it is important to mention how stability effects are introduced without using a potential temperature equation.
Abstract: “for isolating the effects…” this part does not read well, please reformulate.
P1.19: Please add an example of a reference for RANS dealing with wake and blockage.
P1.22: Please add an example of a reference for RANS switching physics components on and off.
P2.23: avoid using “obviously” when stating any modeling hypothesis. “It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so.” - Mark Twain (one of my favorite quotes that is very applicable to science).
P3.15: The ABL formulation does not include an equation for potential temperature so there is an implicit assumption that the equations are only applicable in neutral conditions. However, later on you show results for stable conditions which, in practice, are dependent on the value of lmax. I think that when you start the description of the model in chapter 2 you should make it clear how you are dealing with stability so that the reader knows that the model is more generally applicable that just neutral conditions. This is particularly confusing when you define lmax based on Blackadar’s equation (2) which was meant to be used in neutral conditions. If I understood correctly, as described in the annex and illustrated in Table 1, lmax and other forcings are derived based on best-fit between the desired reference wind conditions and a pre-simulated library of ABL profiles. This is a practical approach to defining these quantities that are not typically measured in real word campaigns. Instead they become tuning parameters of the model to match the desired profile.
P4.16: “it can be used”
P5.Eq.(8): “If we take the wind veer to be much less than (1/Å)dÅ/dz”. It is not straightforward to understand if this assumption holds in general. I guess that the net effect of this assumption is apparent in Figure 1 but you might as well plot the wind veer components vs the wind shear components of eq. (6) to show their relative importance with height and then the approximation will be better substantiated.
P6,8: “This can be seen as an approximation”
P7,26: For completeness, can you specify where this set of constants is coming from?
P8,Figure 2: Please define the symbol “I” of subplot (g) in the text or in the caption.
P9,21: Can you elaborate why z0/lmax is a proxy for normalized ABL depth? Furthermore, why does it “represent a fixed ABL depth or a fixed atmospheric stability?
P12,19: “as an inflow model”
P17,14: “The results are stored as a function”
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RC2: 'Review of wes-2020-130', Fabien Margairaz, 11 Feb 2021
In this work, the authors present a new 1D model for ABL without wind veer (to be used as inflow condition for RANS). The proposed model demonstrates to satisfy Rossby and Reynolds numbers through a few 'numerical proofs'. Finally, the authors demonstrate the use of their model in a series of 1D RANS simulations aimed at wind turbine modeling. The authors also show how the model parameters can be adapted to reproduce the desired profiles.My main comment is: I would recommend adding extra explanations at the beginning of section 2, to clarify for the reader under which atmospheric stability the model is applicable and how atmospheric stability is introduced (especially given that not potential temperature equation are considered). Otherwise, section 2 read as if the model is only valid under neutral stability and the reader might be confused to see that in section 7 stable condition is considered.Overall, the paper is well written and only minor revisions are needed. I recommend this manuscript for publication in WES.# related to my main comment:P3L30 - stability is never mentioned before, make this paragraph confusing for the reader. It your model only valid for neutral stability?P9L23 - "fixed atmospheric stability" How? Maybe I am missing, I am not sure I understand the link with atmospheric stability here.# minor comments:P1L2-4 - "We propose a pressure-driven ... effects of wind veer and ABL depth." Please reformulate this sentence. Maybe expand on 'for isolating the effect of wind veer and ABL depth', as it does not illustrate the goal well.P1L12 - Please add some references to LES and RANS.P1L12 - "Lower fidelity models"? never mentioned again, no example or reference.P1L17-19 - Please add some references for: "In addition, RANS can simulate ... and wake superposition."P1L22 - Please add some references for RANS model with some added or removed "components of ABL physics".P2L23 - I would not use the word 'obviously' here.P2L25 - Please correct: "In the this article,"P2L31 - ASL not defined (P2L4)P4L26 - remove 'here', as it makes this more readableP5L1 - comma misplaced.P5Eq.7 - missing punctuation at the end of the equation.P5L15 - "... \hat S = -(S-G). Thus, we ..."P6L15 - after Eq. (12), use either "with ... as ..., ... as ..." OR "where ... is ..., ... is ..."P7L13 - 'textbook' - maybe consider referencing Eq. (5).P8Fig2 - the overlap of the symbols makes the figure hard to read. In addition, some of the quantity plotted are not explicitly presented (I?). I suggest adding some information in the caption of the figure.P8L3 - "Here, we ..."P9L9 - this does not read well, what 'it' refer to? Please rewrite.P9L12 - "... as long as ..."P9L22 - "... as an inflow model for ..."P11Fig4 (and Fig5) - the choice of colors for is unfortunate for the no veer ones, especially the light green, which is hard too read both on screen and printed. I suggest changing.
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AC1: 'Response to reviewers', Paul van der Laan, 09 Mar 2021
The comment was uploaded in the form of a supplement: https://wes.copernicus.org/preprints/wes-2020-130/wes-2020-130-AC1-supplement.pdf
Maarten Paul van der Laan et al.
Maarten Paul van der Laan et al.
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Short summary
Wind farms operate in the atmospheric boundary layer and their performance is strongly dependent on the atmospheric conditions. We propose a simple model of the atmospheric boundary layer that can be used as an inflow model for wind farm simulations for isolating a number of atmospheric effects, namely, the change of wind direction with height and atmospheric boundary layer depth. In addition, the simple model is shown to be consistent with two similarity theories.
Wind farms operate in the atmospheric boundary layer and their performance is strongly dependent...
Wind Energy Science
The interactive open-access journal of the European Academy of Wind Energy
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