Analysis of Flow Characteristics around a Square Cylinder with Boundary Constraint
Round 1
Reviewer 1 Report
1) Significance of the work could be further highlighted.
2) Further details of the numerical model and test cases could be included.
Also see the comments annotated in the attached, PDF file.
Comments for author File: 
Comments.pdf
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The subject of the submitted manuscript is rather trivial, being treated by many researchers in the past four decades. So, the proposed research does not bring anything new for the scientific community.
The 2D flow simulation is outdated.
The authors miss to describe the numerical approach.
No information regarding the discretization mesh is provided. Nothing is said about the cell size, time step size and so on. No grid convergence test is done.
It is not clear at all whether the numerical simulation is performed for the steady or the unsteady flow.
Conclusions are confusing the reader, e.g. conclusions (4) and (6).
English language is rather poor, so the manuscript needs a substantial improvement. The obsessive repetition of the word "cylinder" should be avoided (I have counted almost 150 appearances, which is far too much) .
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
1. This paper is clearly organized with a thorough investigation in the numerical methods simulating complex fluid flows. However, this journal, Water, is not a computational journal or applied mathematical journal. The authors should add more background information in the introduction to demonstrate on the importance of such a detailed numerical study.
2. Especially, the authors should explain more on the representativeness of the numerical set up in Figure 1. They can find an application scenario of the similar geometry and boundary conditions, for example, scaling in one pipeline, "https://doi.org/10.2516/ogst/2020045", "https://doi.org/10.1016/j.aej.2020.11.043".
3. A validation is needed to verify the reliability of the numerical scheme. The authors should at least analyze the physical consistency of the numerical results. Besides, the convergence accuracy, 1*10^-3, seems a little out-of-date. The authors may defend on this error set up.
4. The authors may inform the CPU time in the simulation. If a long CPU time is needed to achieve this large error criterion, the authors may comment in the concluding remarks that the numerical capability and stability can be optimized further to have a faster convergence.
5. It seems that the authors apply one simple model for a large range of Re numbers. Is it correct? If so, the authors should defend more on the applicability. If not, the authors should clearly state the adjustment of the model in low-Re and high-Re situations.
Author Response
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Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The revised version of the manuscript does not bring any improvement on the overall quality of the paper. Neither in the scientific content, nor in the English language usage. The rebuttal file only contains arguments that are obviously superfluous.
A statement such as "In the future, the improvement of calculation efficiency is a research direction, which can make it possible to apply the research ideas in this paper to three-dimensional simulation." as in the rebuttal file make me emphasize two things that are obvious for the communication with the authors:
1. In my first review I DID NOT TALK about the efficiency. I only discussed things related to the accuracy, which is something very different in CFD indeed.
2. The authors are advised to withdraw their manuscript, perform the needed the deeper investigation admitted by themselves and resubmit it.
Then, a statement such as "Nowadays, two-dimensional numerical simulation is still a widely used simulation method in the research of fluid mechanics." cannot be accepted since almost half of the reference list is older that two decades. Again, I recommend the authors to extend their work to a 3D simulation, when they will find out that the most relevant phenomena are related to the juncture between the cylinder and the basement.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
