Effect of Atmospheric Stability on Meandering and Wake Characteristics in Wind Turbine Fluid Dynamics

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors Alvestad et al. investigated the effect of atmospheric stability on wake deflection and curved flow dynamics in a wind turbine. However, in the reviewer opinion the paper needs minor revisions to be recommendable for publication.

1. The article focuses on the fluid dynamics of wind turbines, which are not mentioned in the title, so it is recommended that the authors consider this issue.

2. In the abstract section, the discussion of the computational results is too cumbersome. It is recommended that the author streamline the content and ensure that the main findings and implications are clearly summarized.

3. In the introduction section, there is too little discussion of the research CFD calculations and vortex flow to ensure that the introduction leads logically to the research question. 1. Multi-field coupling vibration patterns of the multiphase sink vortex and distortion recognition method. 2.  Key technologies and development trends of the soft abrasive flow finishing method.

4. In line 143, the introduction to flow analysis is too brief, and it is recommended that an overview of data processing techniques as well as modeling analysis be added. A similar problem occurs in line 186.

5. The number of grids used does not seem to be the same when using different models. it is recommended that the authors add an explanation of this.

Comments on the Quality of English Language

No

Author Response

Please the attached document.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Summary: The manuscript “Effect of Atmospheric Stability on Meandering and Wake Dynamics” by Alvestad et al. investigates wind turbine wake flows and wake meandering using Large Eddy Simulation (LES). The literature review is fine and the methodology section is thoroughly described. The topic of wake meandering is worth studying and it is of interest to wind energy researchers. However, the key concern for this manuscript is the novelty, and there are some questions on the simulation method that need to be addressed. Further comments are listed below.

 

Major comments:

1.1  The novelty of this study is not clearly presented. The LES of wind turbine wake deflection and meandering has been performed by many researchers. It is suggested that more reference papers should be added in the literature review, especially those for the LES of wake meandering. The objectives of the study on Line 99-106 are too general. The goal of the study must be more specific and the novelty should be defined.

1.2  This study uses synthetic turbulence generation for the atmospheric inflows which is less accurate compared to an LES precursor simulation (see Munters et al. 2016 for reference). There should be a more discussion about the inflow generation method. For instance, the reasons of choosing Mann turbulence generation over a precursor method shall be discussed. Mann model is widely used for ABL modelling and it is a promising approach. However, applying Mann method for non-neutral ABLs may be challenging. The inflows used in this study should be, at least, validated with benchmark data, either LES precursor or field measurement.

[Munters, W., Meneveau, C. & Meyers, J. Turbulent Inflow Precursor Method with Time-Varying Direction for Large-Eddy Simulations and Applications to Wind Farms. Boundary-Layer Meteorol 159, 305–328 (2016). https://doi.org/10.1007/s10546-016-0127-z]

1.3  The atmospheric stability classification was not mentioned in this study. This is very important for the atmospheric stability modelling. What are the stability class for the unstable and stable conditions in the simulations?

1.4  This should be some background on the yaw angle selection in this study. For instance, why the yaw angle of 20 degree was chosen?

1.5  Table 7: There might be mistakes in the dl value. Do you mean dl for Turbine = 1.45 m and for Elsewhere = 6.0 m?

1.6  The difficulties in wake centre detecting for the unstable condition should be elaborated. Please recheck the wake tracking calculation. The wake centre should be able detected beyond 4D downstream for the unstable condition.

 

1.7 There are more results from the LES that can be extracted and analysed. For example, the wake centre dynamics shall be plotted for various positions downstream. The meandering frequency may also be able to associate with the inflows.

 

Minor comments:

2.1  Line 120; there is a typo “will me” instead of “will be”

2.2  In Table A.1 and A.2, the unit of the thrust force must be corrected to [kN]

2.3  Figure 16c: The x-axis label format should be consistent with Figure 16a and 16b, e.g. 1, 2, 3, … instead of 0.5, 1.0, 1.5,…

2.4  Line 430-431: A mistake in starting new paragraph

Comments on the Quality of English Language

N/A

Author Response

Please see the attached document.

Author Response File: Author Response.pdf