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  • Václav Uruba 1,2,*,
  • Pavel Procházka 1 and
  • Daniel Duda 2
  • et al.

Reviewer 1: Mohsen Saffari Pour Reviewer 2: Guojun Yu

Round 1

Reviewer 1 Report

Dear Authors,

Many thanks for your work. It was interesting when you combined your experimental test rig with numerical simulations. However, I saw some parts that needs more revisions! Please find my below comments:

  • First of all your abstract must be provided with some quantitative values! Which I didnt see in your work! For example you need to include some conclusions and results but with numbers and percentages! 
  • Please avoid using the words in keywords which they never showed up in abstract! The sample of such is CFD! You didnt even define what is CFD!
  • The CFD and experiment must be provided with more details. I couldnt see any information about your mesh, computational domain, mesh type, the PC that you did simulations. Moreover, didnt see any details regarding your experimental facilities like their accuracy, and etc...
  • Please add the proper reference for your CFX and mention it in your reference list.
  • Still couldnt understand where is your computational domain! 
  • Why in Figure 14 your inlet lines are provided with an inclined angle and it is not completely fixed! 
  • Please provide the full shape of your experimental rig! How you support the sump pump! I feel a bit dizzy!

Author Response

Dear reviewer, thank you for reading our manuscript and your valuable recommendations. We made our best to include them and thus improve our paper.

  • First of all your abstract must be provided with some quantitative values! Which I didnt see in your work! For example you need to include some conclusions and results but with numbers and percentages!

The abstract was modified, some quantitative conclusions are added.

  • Please avoid using the words in keywords which they never showed up in abstract! The sample of such is CFD! You didnt even define what is CFD!

The CFD is defined in Abstract.

  • The CFD and experiment must be provided with more details. I couldnt see any information about your mesh, computational domain, mesh type, the PC that you did simulations. Moreover, didnt see any details regarding your experimental facilities like their accuracy, and etc...

More detailed info on CFD is now in section 4.2., including some discussion on possible grid independence tests and other computational details.

Accuracy of flow setting is in section 2, accuracy of the PIV measuring method is in section 4.1.

  • Please add the proper reference for your CFX and mention it in your reference list.

The reference is added. The references [17-20] have been added to specify our CFX software and to provide information on physical models used.

  • Still couldnt understand where is your computational domain! 

We added Figure 1a and changed the legend of Figure 2 to specify better the computational domain. In principle, the complete water-filled objects are modelled in the CFD.

  • Why in Figure 14 your inlet lines are provided with an inclined angle and it is not completely fixed! 

The inlet flow into the bellmouth (now Figure 15) is affected by the vessel walls on sides and the bottom. Please note that the water inflow into the vessel is from the side through the mesh – see Figure 1a.

  • Please provide the full shape of your experimental rig! How you support the sump pump! I feel a bit dizzy!

The full experimental rig is now in Figure 1a.

Reviewer 2 Report

Experimental and numerical studies of the vortical structures appearance and their behavior for the flow in a pump inlet sump were carried out. This research is interesting and bears significance. However, the manuscript still needs revision before acceptance. The following comments and suggestions should be considered in the revision.

1.       The relationship between experimental research and numerical research was not well declared.

2.       The numerical method seems to be more important in this research, but nothing about the mathematical model was introduce. Was the model established on an inertial coordinate system or non-inertial coordinate system? Since the authors declared that they considered the coriolis force, the coordinate system should be a non-inertial one. The governing equations and boundary conditions should be provided. In addition, which turbulence model was used?

3.       The grid system used in the numerical simulation should be discussed, as well as the grid-independence test. In addition, the discretized schemes for the disretization of the governing equations should also be introduced.

4.       How do the authors validate their numerical model? Since they have experimental data, why not validate the numerical results by some of the experimental data?

Author Response

Dear reviewer, thank you for reading of our manuscript and your valuable recommendations. We made our best to include them and thus improve our paper.

  1. The relationship between experimental research and numerical research was not well declared.

We added Figure 1a and changed the legend of Figure 2 to specify better the computational domain.

  1. The numerical method seems to be more important in this research, but nothing about the mathematical model was introduce. Was the model established on an inertial coordinate system or non-inertial coordinate system? Since the authors declared that they considered the coriolis force, the coordinate system should be a non-inertial one. The governing equations and boundary conditions should be provided. In addition, which turbulence model was used?

Much more details on CFD methods and tools have been added into chapter 4.2, including the rotating and stationary subdomains and Coriolis forces resulting from the earth rotation.

We do not describe formulas in the governing equations for the fluid flow, cavitation and turbulence models, but still we consider it to be a reasonable compromise, because full description of the URANS equations, VOF model, Zwart model and SST/SAS models (including definitions of the blending functions and all used constants) would take a lot of space (several new pages), and it is not in the scope of this paper, because no significant changes have been done comparing to default settings used in the ANSYS software.

Also, new references [18-20] have been added to specify turbulence models used.

  1. The grid system used in the numerical simulation should be discussed, as well as the grid-independence test. In addition, the discretized schemes for the disretization of the governing equations should also be introduced.

We added more details on computational grids and discretization schemes into chapter 4.2, including some discussion on possible grid independence tests.

  1. How do the authors validate their numerical model? Since they have experimental data, why not validate the numerical results by some of the experimental data?

Some basic validation has been done by comparing hydraulic parameters of the pump and all the rig performance simulations with measured integral data (e.g. flow rate and pressure losses). Basic calculated vortical structures have been compared with the visualizations in Figures 5-6 and 9-11. Also, the chapters 5.2, 5.3, 5.5 aim the validation of the numerical results by experimental data.

Round 2

Reviewer 1 Report

Dear Authors,

Many thanks for the revised version. Now, I can see that the paper has been revised completely and all my comments have been replied. The only problem is that: Please add some numbers and quantitative values or percentages from your results in abstract to motivate readers to read and follow your work! Writing in general wouldnt help your followers to catch your all concerns about this topic! 

Author Response

Dear reviewer,

Thank you for your patient and careful reading of our paper. We appreciate your valuable comments.

We reworked the Abstract and added some information to motivate the possible reader.

Again, thanks a lot for your help in improving the paper.

Reviewer 2 Report

The comments raised by the reviewer have been addressed, and therefore it is recommended for publication.

Author Response

Dear reviewer,

Thank you for your patient and careful reading of our paper. We appreciate your valuable comments which helped to improve the paper.