Mathematical Model for the Movement of Two-Pipe Vehicles in a Straight Pipe Section

Round 1

Reviewer 1 Report

Dear authors,
This paper provides very interesting results, and the research topic is within this journal's scope. However, the manuscript is poorly written and organized. Some major revisions are recommended.

General comments:

1. Despite the said general merits of the work, the manuscript has some weaknesses, and the main of them is that novelty is highlighted too little, especially in the Abstract and Introduction sections.

2. It would be better if the methodology part (i.e., section 2.2.) is explained better, specifically the processes of the design phase.

3. Conclusion section can be shortened/made concise in two paragraphs,  and talk about the application for water resources managers.

4. Extensive editing of the English language is required.

Specific comments:

L 23: Here, talk about the application of this manuscript for water resources managers.

L 459: Before the conclusion section, I would like to see a heading about research implications and another heading about the research limitations.

Author Response

Dear expert:

Thanks for the valuable comments from the experts, your suggestions are of great help to the improvement of the paper. The content of the paper has been revised according to your suggestions, and the specific reply is as follows:

Question 1: Despite the said general merits of the work, the manuscript has some weaknesses, and the main of them is that novelty is highlighted too little, especially in the Abstract and Introduction sections.

Reply：The abstract and introduction sections of the article have been rewritten, focusing on the novelty of the paper and its guiding role in engineering practice.The innovation of this paper is to solve the equation of motion of the two-pipe vehicles by constructing a mathematical model, which provides a theoretical basis for the rapid construction of the transportation system, and can save the cost of system construction at the same time.The specific revisions can be found in the paragraphs marked in red in the abstract and introduction.

Question 2: It would be better if the methodology part (i.e., section 2.2.) is explained better, specifically the processes of the design phase.

Reply：Section 2.2 has been revised based on your suggestion. The design and operation process of the two-pipe vehicles are described in detail, and the force of the two-pipe vehicles is described in detail. During the derivation of the equations of motion, the source of each equation is described in detail.The specific revisions can be found in the paragraphs marked in red in the abstract and introduction.

Question 3: Conclusion section can be shortened/made concise in two paragraphs, and talk about the application for water resources managers.

Reply：Based on your suggestion, simplify the conclusion into two paragraphs and highlight the guiding role of the research content for water managers. Section 4.3 is added before the conclusion, mainly to describe the research significance and limitations of this paper.

Question 4: Extensive editing of the English language is required.

Reply：For the language problem of this article, please ask the mdpi professional language editing agency to modify it.The revised certificate is attached here.

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors tried to establish the simplified N-S model during stable movement of the two-pipe vehicles. Then the model is displayed in a cylindrical coordinate system. Experiments verified the correctness of the derivation. I believe this manuscript needs minor revision before its acceptance for publishing on Water.      

Specific comments follow with line numbers in brackets:

L54: “ the method of model test and… ” to “the model test and …” 

L78: “ experience” to “experiences ”.

L117: “The Navier-Storkes equation is …” to “Navier-Stokes (N-S) are …”

L186:”movement” to “movements”

L286: “ LDA” should be “LDV” in a professional way.

Author Response

Dear expert:

Thanks for the valuable comments from the experts, your suggestions are of great help to the improvement of the paper. The content of the paper has been revised according to your suggestions, and the specific reply is as follows:

1.The introduction part is rewritten to give a comprehensive and in-depth introduction to the research background of this paper, emphasizing the research purpose of this paper. The specific modification content can be found in the introduction section of the text.

2.The conclusion part of the paper is abbreviated and improved, and the guidance and help of the research results of this paper to engineering practice are more prominent. Detailed revisions can be found in the conclusion section of the text.

3.For the language problem of this article, please ask the mdpi professional language editing agency to modify it.

4.The "the method of model test" has been changed to "the model test and …"

 "experience" has been changed to " experiences "

"The Navier-Storkes equation is …" has been changed to "Navier-Stokes (N-S) are …"

" movement" has been changed to "movements"

  "LDA" has been changed to "LDV"  

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I would like to thank the authors for addressing my comments. The manuscript is significantly improved, and so I recommend acceptance.