Study on the Law of Diesel Oil Carrying Water in Lanzhou–Chengdu–Chongqing Product Oil Pipeline Based on Large Eddy Simulation
Round 1
Reviewer 1 Report
The paper contains some interesting results. However, it needs to be improved in many points in a major revision, prior to a possible acceptance. These are summarized below:
1. The discussion on the y+ value in connection to Fig. 6 is not convincing. I have the impression that the cited reference exists only in Chinese. Beyond the question of the suitable range of y+ values: What is the near-wall treatment/model at all that is used to amend LES, including the question of the behaviour of the subgird.scale model ?
2. What do the dotted and solid lines mean in Fig 6 ?
3. Fig. 6: For L<10m, at an axial position a single y+ value is observed. Does this mean that thy y+ value is perfectly uniorm around the periphery of the pipe at each axial position ? This cannot be, just because of the fluctuating behavior of the flow.
4. What velocity is shown in Fig. 5 ? Velocity at a time step, or the time averaged velocity ?
5. The proof of the adequacy of grid based on Fig. 5 is insufficient. The position of this plot is in the iniial part, where the flow features (at least according to the pediction) are not strongly fluctuating. Further evidence for the grid independence is needed.
6. What is the time step size ?
7. The font size of the text in some figures is too small (e.g. Fig.14).
8. Line 153: Figure 1 → Figure 4
9. The initial conditions must be defined more precisely. What are the iniial conditions at the beginning of the simulation ? At the beginning, I assume that the water region is patched into the field accoding to Fig 4. What is the assumed velocity field at this moment of time ?
10. Fig. 5 shows the water region at a cross section. However, what is the length of the assumed water region in the axial direction (along the pipe length) ?
11. What are the inlet boundary conditions in detail ? Is the time-averaged velocity constant, or is a profile assumed ? Are fluctuations imposed at the inlet ?
12. Figure 3a: Quality? How is quality defined/quantified ?
13. Figure 3: What do the numbers tell that are shown in the figure? Do they mean that the grid is good (how good?), why ?
14. Line 122: structured mesh → block structured mesh
15. Line 103: „Sigma“ is the „surface tension“ isn‘t it ?
16. Abstract, Lines 10-13: The sentence „In this paper, …“ is too long, difficult to understand. Additionally, it creates the wrong impression as if experiments were performed (through the word „prototype“) and should be reformulated (in more than one sentences).
17. Abstract, Lines 23-25: The last sentence „In addition …“ should also be reforrmulated in two sentences (expressing the two statement in two separate sentences).
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Dear author,
I would like to suggest you to compare your simulation results with standard model available. Also, rewrite the conclusions mentioning silent findings. I also suggest include more literature to support your claim.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The authors used the LES method to the simulation of a certain volume of water flow in the elbow of oil pipelines. The paper was prepared at a high level, and the simulation method was confirmed by mesh reduction and the comparison of the results, and also by the comparison of experimental and numerical results. Four models for 5 different velocity inlet were analyzed.
The results were presented very well, but they have not a universal character. The analysis of results is poor and there is no attempt to relate the results to general laws or relationships. All presented results relate only to this specific case and it will be difficult to apply them to other models - only in the case of fig. 20, an attempt was made to generalize the results. That's the only serious objection I have.
I also don't understand why the Y-axis in fig. 14 is described as "Inclination"? On this axis, the velocity is presented. I understand the idea, but for me it is confusing.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors gave satisfactory answers to my question and improved the paper by a revision.
However, I think that a further revision is necessary.
The reason is:
The authors gave me some explanations/answers, however, this information should not necessarily be directed to me personally, but to the readers of the paper for their better understanding.
Therefore, I suggest that some of the answers/expalnations I received should also be implemented in the paper.
These refer to the following points:
Point 4, Point 6, Point 9, Point 10, Point 11
Author Response
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Author Response File: Author Response.pdf
