Numerical Study of Turbulent Wake of Offshore Wind Turbines and Retention Time of Larval Dispersion

Round 1

Reviewer 1 Report (Previous Reviewer 1)

The authors addressed all comments, I can accept the manuscript now.

Author Response

Dear Reviewer,

Thank you for your helpful report.

On behalf of the co-authors.

Souha Ajmi

Reviewer 2 Report (Previous Reviewer 2)

Dear authors, the revised version is improved and hence can be considered for publication. Please address the following comments:

1. The ending of the conclusion is not acceptable. Avoid putting references in the conclusion section.

2. " In a second step, the numerical results will be 484 compared with in situ observations recorded during the winter 2023, at scale 1 and near a 485 gravity-based foundation, in terms of hydrodynamics and larval concentration" This should be in future scope or may be this sentence is not going with the whole paragraph. Better revise.

Proofreading is required before final acceptance.

Author Response

Dear Reviewer,

Thank you for your helpful comments that helped to improve the manuscript.

We have taken your comments into consideration.

On behalf of the co-authors.

Souha Ajmi

Author Response File: Author Response.pdf

Reviewer 3 Report (Previous Reviewer 3)

Thank you for taking into consideration my comments. The manuscript is now ready for publication.

A final proofreading is very helpful.

Author Response

Dear Reviewer,

Thank you for your helpful comments.

On behalf of the co-authors.

Souha Ajmi

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The article describes a model application for simulating hydrodynamics and particle transport around an offshore wind farm foundation. The simulations are sound and interesting, but rather simplified situations were considered only: free surface effects were neglected, turbulent dispersion of particles was neglected, particle floating or sedimentation was neglected, tidal and wind inflluences were not considered. There are so far only very few or limited new findings or contributions.

Very critical is also a completely missing comparison with literature studies, calibration or validation. There is no proof at all that the results are sound. 

l. 65 and others: it seems that k-epsilon has been misedited to k-!. Please check and correct.

l. 114: The authors use a scaled model, which is typical for lab studies, but not necessary for numerical studies. What is the justification for that? And why a scale of 1:10 has been used? What implications with respect to scale differences are expected? And did the authors check the Reynolds and Strouhal number to be in the right regime?

Furthermore, Froude scaling indicates free-surface flow. However, it seems that the model is setup with a rigid lid surface. This seems to be a significant simplification. The authors need to justify that and quantify implications.

l. 135: What is “large computing time”? Please specify CPUs and machines used, as well as durations. And why not using a coarser grid for the mesh convergence study? The argument is not really convincing. What are current Courant numbers?

l. 137ff: Why using a uniform profile and not a logarithmic profile? Did the authors check if the distance to the monopile is sufficient to develop the bed boundary layer completely? And what wall-law has been used at the no slip bed boundary? Any data to compare with from field or lab?

Why only simple boundary conditions (uniform, constant flow) have been analyzed? Coastal flows are influenced also by wind and tides and stratifications. How would those affect the transport. Are those computations possible, have they been reported in literature?

l. 170: It seems the particles only follow the mean velocity field, and do not have a random walk like component in it, to represent turbulence fluctuations. Has that been considered? What are the effects of it? There are lots of other particle tracking algorithms having that embedded, including the spatial variation of it.

Furhtermore particles like larvae have mass and volume and can be either positive or negatively buoyant. Both can be represented as positive or negative settling velocity, as done in several particle tracking algorithms. Why hasn’t that been considered here? And what about the boundary conditions for the particles. Do they stick at the surfaces or simple are reflected? How is this represented in the code? And can particles accumulate (like flocking) or desagregate due to turbulence? Doesn’t look like that, but should be mentioned as limitation.

Figure 8: The position of where the velocity magnitude has been computed is not clear. Is it at the surface? Shouldn’t the velocity then not be higher then .31m/s? Showing some profiles would help here too. And where do the oscilations come from? Are they related to the vortex shedding? Choosing another point upstream would help to see that clearer. Has the vertical profile been fully developed?

Figure 16: I do not really like the figures of no of particles vs. time. They are not clear for me either. Would be good to think working with concentrations associating initial concentrations with downstream locations. Or working with fluxes to identify regions with higher or lower transport characteristics.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Commendable job by authors dealing as they dealt with every possible point of query in the manuscript. I would recommend this work for publication with the following minor points which must be addressed.

1. Abstract: The abstract is a bit vague in nature.  It doesn't include the objectives or any slight idea of the core objective of the paper. Try including the terms "effects of the magnitude and direction of flow velocity,  type of foundation, release type", models used and some stats to conclude the abstract.

2.  In table 1 correct the spelling of minmum and maxmum to minimum and maximum.

3. The formatting of images needs a rework. As Fig.9 is completely out of order. Try reformatting.

4. The conclusion is not very crisp in nature. It sounds very usual. It is suggested that authors need to rewrite this section stating the major findings and concluding on the basis of the same.

5. The limitations and future scope of this work are a great add-on to this manuscript. The hypothesis needs to be challenged by the authors so that the readers can be sent in the further direction of new findings.

The draft is almost there to be accepted. The quality of English used is worth considering. 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Review on “Turbulent wake of offshore wind turbines and retention time of larval dispersion”

by Ajmi et al.

Manuscript ID: jmse-2362245

A- General Comments

The paper in hand concerns a numerical study of the impacts of OffshoreWind Farms (OWFs) on larval dispersion. At the scale of OWF foundations a combination of two numerical models is used: an Eulerian model OpenFoam, solving the 3D Navier-Stokes equations for computing the hydrodynamics, and a Lagrangian model Ichthyop, solving the advection-diffusion equation for simulating the larval dispersal. Particularly, it was shown by authors that the influence of foundations might lead to a stepping-stone effect for gravity-based geometry with spring tide event

The topic of the paper is interesting, within the scope of the journal, and worthy of investigation. The originality of the work is acceptable and the study performed is adequate. However, the manuscript deserves a major revision. I suggest that authors take into account the comments and questions below before it can be accepted for publication in Journal of Marine Science and Engineering.

B- Detailed Comments and questions

Title

Details on how the study was performed (theoretical, numerical, or experimental) should be added to the title, for instance numerical study.

Abstract

1- It is not clear whether the originality of the work resides in the study of the impacts or the numerical modeling itself or both of them? Please clarify.

2- Explicit results with numbers should be provided at the end of the abstract.

Keywords

Keywords are ok.

1- Introduction

1- References relevant to Journal of Marine Science and Engineering should be added, if possible.

2- The introduction can be shortened by focusing more on the research gap in the field and the originality of the work.

2- Numerical methodology

1- References to most of the equations presented should be provided.

2- The mesh characteristics presented in Table 1 should be argued.

3- What about the precision and accuracy of the simulation method presented?

3- Results and discussion

1- There are a lot of interesting observations without deep analysis. More physical analysis is to be added to this section by shortening the quantity of results shown if needed;

4- Conclusions

The main outputs of the work in terms of applications should be highlighted.

5- References

References relevant to Journal of Marine Science and Engineering should be added, if possible.

The manuscript deserves an english proofreading.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Thank you for taking into consideration my comments. The manuscript is now ready for publication.

English Lanaguage is ok.