Numerical Investigation on Air–Water Two-Phase Flow of Jinping-I Spillway Tunnel
Muhammad Yousaf Malik
Round 1
Reviewer 1 Report
Review Report-Applied Mathematics (ID 5562667)
Title: Numerical investigation on air-water two phase flow of 2 Jinping-I spillway tunnel
This article focuses on better understanding of ventilation mechanism. The air-water two phase flow is simulated un- 16 der the Euler-Euler framework. A hybrid drag model, which is verified by the prototype data of 17 Jinping-I spillway tunnel, is proposed to improve the prediction of air demand and air entrainment. 18 Based on the new drag model, the air entrainment behind aerators, air velocity distribution in the 19 air ducts and the residual space of the tunnel are systematically analyzed. The work is significant and may be accepted for publication in Applied Mathematics. However, I must suggest some minor revisions
- In nomenclature add the units also for physical quantities.
- Validate the results by comparing with already published work.
- Language must be revised to fix lot of errors.
- Qualitative results must be mentioned in abstract.
- Conclusion must be improved.
- It would be better if authors highlight the state of art of study in introduction section.
- Cite recent studies to comprehend literature review properly with their order of appearance.
- Some recent studies to comprehend literature are given below.
https://doi.org/10.1002/mma.8234
https://doi.org/10.1016/j.csite.2022.101934
https://doi.org/10.1016/j.csite.2022.101851
https://doi.org/10.1016/j.joes.2022.02.002
https://doi.org/10.1177/09544062211068777
https://doi.org/10.1016/j.asej.2021.01.017
Recommendation: The article may be accepted for its publication provided that the authors address the queries given above.
Author Response
To reviewer #1:
Dear reviewer:
Thank you for your time. The comments and suggestions are very helpful for the improvement of our work. I would like to give a point-to-point reply to your comments and suggestions.
Point 1: In nomenclature add the units also for physical quantities.
Response 1: There is no nomenclature requirement in the manuscript template from the website of Applied Sciences-Basel journal. In order to meet the format requirements of the journal, we did not add nomenclature. However, we have carefully checked all the physical quantities and make sure that they are explained properly.
Point 2: Validate the results by comparing with already published work.
Response 2: The simulation results of average aeration concentration and total air demand have been compared with the prototype data from reference [21].
Point 3: Language must be revised to fix lot of errors
Response 3: we have extensively examined the spelling and typo of our manuscript for several times again.
Point 4: Qualitative results must be mentioned in abstract.
Response 4: we have added qualitative expression, the air demand prediction error is less than 18.9%, while the air entrainment prediction error is less than 28.35%, in the abstract.
Point 5: Conclusion must be improved.
Response 5: We made a more careful summary of our study again and minorly revised the conclusion.
Point 6-8: It would be better if authors highlight the state of art of study in introduction section. Cite recent studies to comprehend literature review properly with their order of appearance. Some recent studies to comprehend literature are given below.
Response 6-8: we have read the given comprehend literature and choose some relevant important work about stratified flow to cite to highlight the state of art of study in our introduction section.
Reviewer 2 Report
The work is CFD simulation of flow pattern study of two phase flow of air and water. Based on the existing models, a hybrid model is developed. Accordingly two flow patterns were identified depending upon the dragging capacity of water and the air entrapment situations are studied.
The work is a simulation study, based on the available proto type data. The authors need to also add the interfacial flow pattern under these flow conditions. This will help visualizing the air entrapment cases with clarity.
Author Response
To reviewer #2:
Dear reviewer:
Thank you for your time. The comments and suggestions are very helpful for the improvement of our work. I would like to give a point-to-point reply to your comments and suggestions.
Point 1: The work is a simulation study, based on the available proto type data. The authors need to also add the interfacial flow pattern under these flow conditions. This will help visualizing the air entrainment cases with clarity.
Response 1: We quite agree that the interfacial flow pattern under different flow conditions will help visualizing the air entrainment cases with clarity. However, it’s difficult to take pictures during the prototype observation in spillway tunnel. In additions, the air velocity profiles, water velocity profiles and the VOF profiles from CFD in the Figure 5 and Figure 8 can indicate the interfacial flow pattern to some extent. We have to admit that the numerical simulation in our study cannot distinguish the regimes of spray flow, stratified flow, wavy flow or other regimes, because the limitation of the VOF or Euler-Euler multiphase model with coarse (relative to bubbles) grid resolution.
Reviewer 3 Report
Corrections of the manuscript are required according to the following comments;
- It is better to change the terminology, "condition number" into "gate opening ratio" in the whole text. That is, condition No. 1 -> 25% gate opening ratio.
- I cannot find the aerator No. 2 and No. 4 in Figure 1. Please specify them in the figure. Also, how about change the No. 2 and No. 4 into No. 1 and No. 2, respectively?
- Some errors in the text : preliminary study22, properties23->preliminary study[22], properties[23].
- In Figure 4, it is better to insert "Simulation:" as is in Figure 7 in order to prevent misunderstanding.
- In your hybrid model of equation (9), what's the value of epsilon? Why did you use e^2 instead of e? If you use more optimum value of e, the hybrid model will agree very well with the prototype. Please propose an optimizing process of the epsilon value.
Author Response
To reviewer #3:
Dear reviewer:
Thank you for your time. The comments and suggestions are very helpful for the improvement of our work. I would like to give a point-to-point reply to your comments and suggestions.
Point 1: It is better to change the terminology, "condition number" into "gate opening ratio" in the whole text. That is, condition No. 1 -> 25% gate opening ratio.
Response 1: we have examined the manuscript and change the terminology, "condition number" into "gate opening ratio" in the whole text.
Point 2: I cannot find the aerator No. 2 and No. 4 in Figure 1. Please specify them in the figure. Also, how about change the No. 2 and No. 4 into No. 1 and No. 2, respectively?
Response 2: we have revised the Figure 1 to specify the aerator No. 2 and No. 4. In additions, data from prototype observations is precious and we have only the prototype data of aerator No. 2 and No. 4. Therefore, we cannot change the No. 2 and No. 4 into No. 1 and No. 2 respectively.
Point 3: Some errors in the text : preliminary study22, properties23->preliminary study[22], properties[23]；
Response 3: we have extensively examined the spelling and typo of our manuscript for several times again.
Point 4: In Figure 4, it is better to insert "Simulation:" as is in Figure 7 in order to prevent misunderstanding.
Response 4: we have revised the Figure 4.
Point 5: In your hybrid model of equation (9), what's the value of epsilon? Why did you use e^2 instead of e? If you use more optimum value of e, the hybrid model will agree very well with the prototype. Please propose an optimizing process of the epsilon value.
Response 5: The hybrid model is the combination of the Schiller and Naumann model and Symmetric model. The blending coefficient, epsilon, is choose as the percentage of gate opening. The e^2 is used because we find the prototype results is closer to the results from Schiller and Naumann model for large gate opening, while the results is closer to the result from Symmetric model for small gate opening. Furthermore, the linear coefficient epsilon (0-1) is not sufficient to describe this difference, while the quadratic coefficient e^2 and 1- e^2 can get better results. In additions, the computational expense is too large on the numerical simulation to support an optimizing process. We plan to conduct a large-scaled model test in the future to get enough data, so as to propose an optimizing process of the epsilon value.
