Numerical Study of Effect of Sawtooth Riblets on Low-Reynolds-Number Airfoil Flow Characteristic and Aerodynamic Performance

Round 1

Reviewer 1 Report

Review of the manuscript ID: processes-1432811Type of manuscript: Article

Title: Numerical study of Riblets on low-Re airfoil flow separation and aerodynamic performance

 

Overview and general recommendation:

 

The paper is interesting but it cannot be recommended for publication in Processes in the present form. The paper is written carelessly and English is incomprehensible. Basic technical terminology is used out of blue, what makes the paper illegible. I must reject the paper for publication in Processes but after major corrections it may be considered once again.

Detailed comments are as the following:

 

• The title must be improved; the reader do not exactly know what about is the paper; good practice indicates not to use here any abbreviation; moreover, the word ‘riblets’ seems to be too little precise; what kind of ribs the authors are talking about? ‘Heating fins’ sound more technical.
• The abstract needs to be rewritten for better wording and flow. Its narrative flow should give a better feel for overview of the covered topic to be a single and connected work. Should be given information about the software used, methods, the aspects dealt with in the investigation and so on. The basic mathematical results should also be delivered.

The reader should be informed about simulation method and numerical tools applied as well.

The reader exactly know very little about the results and the scientific goals.

• In the text, the authors use the term of ‘drag reduction’. I think ‘resistance’ is the wright option.
• Introduction section is for correction. There is no correspondence between the paper and the presented overview. The description looks like an introduction to a popular science article not research original paper.
• The text is written carelessly and English is incomprehensible.
• It should be also better explained numerical investigations and the used software.
• The abbreviation first used in the paper should be explained, e.g. NACA.
• How equation (18) is adopted to the Authors’ investigation? Algorithm of the model, need to be attached.
• What statistical analyses say about the validation?
• English should be checked and improved by native speaker.
• Please, deliver other thermodynamic parameters of the medium.
• It is required to find and explain the correspondence between presented computational model and the governing equations used for the simulations.
• What are exactly input data. Boundary conditions are also omitted.
• The paper is computational study but in my opinion the process and phenomenon should be introduced as an additional figure to explain the utility goal of the study.
• The conclusions should state in a clear and complex manner the findings of the performed study. The presentation of the conclusions should be improved. In fact, little is known about the results.

 

I strongly recommend the Authors to learn the right construction of the scientific paper and to read closely guidelines for authors.

Comments for author File: Comments.docx

Author Response

Thank you for your comments on the manuscript. We appreciate them very much and have tried our best to revise the manuscript. Please see the attachment for detailed responses.

Author Response File: Author Response.pdf

Reviewer 2 Report

In the present study authors, sawtooth riblets with different lengths and groove widths were arranged in the airfoil suction surface(SS). The study seems interesting; however, the following concerns must be addressed before being considered for the journal. 
Why NACA 4412 is selected for the current study? Would the enhanced performance with the ribs results be applied to the chosen airfoil only?
Why was the effect on the ribs studied on the low-pressure side only? 

During the mesh optimization study, an optimized number of nodes for the ribs was also evaluated. Which mesh distribution in the rest of the domain was considered during the study, as mentioned above? 

Author Response

Thank you for your comments on the manuscript. We appreciate them very much and have tried our best to revise the manuscript. Please see the attachment for detailed responses.

Author Response File: Author Response.pdf

Reviewer 3 Report

Reviewer #: The paper presents an interesting approach to a complex matter; however, some aspects must be improved in order to be considered for publication
  

1. A complete review of grammar and style must be done in order to improve the quality of the publication.
2. The authors must rewrite the abstract in order to better present their findings because it is difficult to follow and to understand what exactly they have found.
3. The motivation for this publication is not clear from the introduction
4. How the Reynolds number have been calculated in this paper?
5. The numerical model should be verified and validated in accordance with the rules for CFD V&V. Otherwise, it is not possible for the reader to judge the quality of the results
6. The authors would have to prove that the k-omega-SST model is as
   Accurate as any other two equation model for the stated applications.
7. The quality of figure 3 should be improved
8. Even though it is not the main purpose of the study, it might be a good idea to expand the conclusions with practical design recommendations based on their numerical/experimental studies.

Author Response

Thank you for your comments on the manuscript. We appreciate them very much and have tried our best to revise the manuscript. Please see the attachment for detailed responses.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Compared to the first version of the manuscript, the present revision shows much more improvement.