PONE-D-20-26743

Hydrodynamical energy-saving analysis of parallelly swimming fish

PLOS ONE

Dear Dr. Torisawa,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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Roi Gurka

Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: N/A

Reviewer #2: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: No

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Thanks for the oppertunety to review this paper.

This paper applied the kinematic equations extracted from real fish to CFD to study how fish can improve efficiency in groups. Detail analyses of the conducting and analysing the CFD are given. It is great to see this study improve the accuracy of the CFD by including the real fish's kinematics. The main issues of this current versions are:

1. In the abstract and title claim that this paper talks about the energy-saving, however, most of the paper focused on the CFD method and verifications of the CFD results. The report of the energy-saving in schools is very limited and simple. The mechanism of energy saving (gaining higher efficiency reported in this paper) is not given. There are many papers report the hydrodynamic interaction mechanism of energy saving in schooling fish swimming side-by-side. This paper did not have a detail comparisons, discussions and analyses with them. e.g.

Huertas-Cerdeira, C., B. Fan, and M. Gharib, Coupled motion of two side-by-side inverted flags. Journal of Fluids and Structures, 2018. 76: p. 527-535.

Bao, Y., et al., Dynamic interference of two anti-phase flapping foils in side-by-side arrangement in an incompressible flow. Physics of Fluids, 2017. 29(3): p. 033601.

Dewey, P.A., et al., Propulsive performance of unsteady tandem hydrofoils in a side-by-side configuration. Physics of Fluids, 2014. 26(4): p. 041903.

Li, G., et al., On the energetics and stability of a minimal fish school. PLoS ONE, 2019. 66(2): p. 596023.

Dong, G.-J. and X.-Y. Lu, Characteristics of flow over traveling wavy foils in a side-by-side arrangement. Physics of Fluids, 2007. 19(5): p. 057107.

2. Another main issue is the writing. I recommend the authors rewrite the title and abstract to summarise this paper's work accurately, and reorganise the paragraphs according the to the nice logic. For example, Page 18 Line 291-294, those body wave comparisons should be given near the Section Formulation of swimming motion. Introduction should be more related to the novelty in this paper, (to me it is applying real fish kinematics to CFD, if the authors give the new mechanism of energy-saving, then it should be this).

minor comments:

1. An extral space at "Biwa salmon ( Oncorhynchus)" in the abstract in the system.

2. Page 2 Line 21-25, sentence is too long.

3. Page 5 Line 66 It says "the purpose of this study was to clarify the effect of parallel swimming in a group ...", this seems different from the title and abstract. Please change to keep consistent.

4. Table. 1, how many fish are measured? And move the description of the permit at Page 16 Line 262 here, as these should be given in the methods instead of CFD results.

5. Page 7 Eqs. 1-3, clarify the unit of the varibles.

6. Page 8 Line 121 what is the unit of 0.25? BL or meter?

7. Page 8 Line 123, Should "x<0.25" be "x>0.25"?

8. Page 14 Line 214, report Renoylds number

9. Page 14 Line 222, report flow speed in CFD

10. Page 16 Line 256, you also need to point out Froude efficiency mainly works if the fish is accelerating or decelerating. See a nice paper discussed this problem: Maertens, A.P., M.S. Triantafyllou, and D.K.P. Yue, Efficiency of fish propulsion. Bioinspiration & Biomimetics, 2015. 10(4): p. 046013.

11. Page 17 Line 274 Please also report the R value for the fitting. or any other values which can tell how good the fitting is.

12. Page 18 Line 280, from which figure we can get this claim? What is the phase shift value?

13. Page 18 Line 291 add the table ref or the value for the claim "was closest to 1"

12. Page 20 Line 320, new paragraph after the caption of the figure

13. Page 21 Line 328, report which line shows the "10%" energy saving?

14. Page 21 Line 339-341, this is the point of Weihs (1973 Nature) paper, please cite. Also, you need to mention this is valid when two fish swim out-of-phase.

15. Page 23 Line 366, this can also be due to the 3D body shape as you did not copy the morphology. And 3D effect of simulation can also be an explanation. See this paper, Verma, S., G. Novati, and P. Koumoutsakos, Efficient collective swimming by harnessing vortices through deep reinforcement learning. Proceedings of the National academy of Sciences of the United States of America, 2018. 115(23): p. 5849-5854.

16. Page 24 Line 383 what are the "new insights"?

Check the references carefully. Some have dois (e.g. [1]), some do not (e.g. [2]). Some even have different font size (e.g. [11]).

Fig.1 give information of the view angle, side view or top view?

Fig.9 give line legend

Fig. 11 add the coordinate to show the direction of x

Fig. 13 line legend is missing

Reviewer #2: The study does not provide the non-dimensional number such as Reynolds number and Strouhal number

There are also grammatical and spelling mistakes in the manuscript.

There are no validations for the code

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Reviewer #1: No

Reviewer #2: No

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PONE-D-20-26743R1

Hydrodynamical effect of parallelly swimming fish by using CFD method

PLOS ONE

Dear Dr. Torisawa,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please address adequately the reviewer concern and make a proper connection between the simulations, fish and previous research work in this field.

Please submit your revised manuscript by Mar 29 2021 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

We look forward to receiving your revised manuscript.

Kind regards,

Roi Gurka

Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #2: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: (No Response)

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Dear editor and authors,

Thanks for the opportunity to review this paper. And thank the authors addressed my most comments. But sorry, I can not accept as this because I still do not think the reviewer did nicely summarise the major contribution of the work.

I do not agree that the major contribution is “applied the real fish kinematics to CFD analysis ”. Because the authors did not really apply the kinematics of real fish frame by frame. Instead, they extract the key parameters from the real fish system and then simulated by the fitted body wave function. This is done by many recent works such as:

Li, G., Kolomenskiy, D., Liu, H., Thiria, B. and Godoy-Diana, R., 2019. On the energetics and stability of a minimal fish school. PloS one, 14(8), p.e0215265.

Li, L., Nagy, M., Graving, J.M., Bak-Coleman, J., Xie, G. and Couzin, I.D., 2020. Vortex phase matching as a strategy for schooling in robots and in fish. Nature communications, 11(1), pp.1-9.

And the authors mentioned that “there are no published studies on the calculation of the thrust and drag forces from the pressure distribution on the body …” However, the truth is there are many. For example:

Dabiri, J.O., Bose, S., Gemmell, B.J., Colin, S.P. and Costello, J.H., 2014. An algorithm to estimate unsteady and quasi-steady pressure fields from velocity field measurements. Journal of Experimental Biology, 217(3), pp.331-336.

Gemmell, B.J., Colin, S.P., Costello, J.H. and Dabiri, J.O., 2015. Suction-based propulsion as a basis for efficient animal swimming. Nature communications, 6(1), pp.1-8.

Lentink, D., Haselsteiner, A.F. and Ingersoll, R., 2015. In vivo recording of aerodynamic force with an aerodynamic force platform: from drones to birds. Journal of The Royal Society Interface, 12(104), p.20141283.

I would really suggest the authors do read the related literatures and summary nicely about the contribution in the abstract and introduction.

Reviewer #2: Dear Writer

The strouhal number should be in the manuscript. It is not mentioned in the manuscript.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: Yes: Liang Li

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Hydrodynamical effect of parallelly swimming fish using computational fluid dynamics method

PONE-D-20-26743R2

Dear Dr. Torisawa,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Roi Gurka

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: N/A

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: I thank the authors for their answers to my comments. The quality has been greatly improved. Therefore, I support to publish.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

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Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: Yes: Liang Li