A 3D Fully Non-Hydrostatic Model for Free-Surface Flows with Complex Immersed Boundaries
Round 1
Reviewer 1 Report
Review of manuscript “A 3D fully non-hydrostatic model for free-surface flows with complex immersed boundaries” by Der-Chang Lo and Yuan-Shiang Tsai.
The Authors present a hydrodynamic numerical model for the simulation 3D free-surface flows, based on the numerical solution of the Navier-Stokes equations, and the Volume of Fluid and Immersed Boundary methods. The model is validated against experimental measurements of velocity and impact force for dam-break flow over a vertical square cylinder. Several case studies have been simulated regarding full and partial dam break flows over geometries of different shapes (cylindrical, rectangular or square).
The paper is interesting and well-structured. A variety of cases have been simulated and the results are quite nicely presented. However, I have noticed some important shortcomings which should be addressed in order to improve the quality of the manuscript.
My opinion is that that the manuscript might be accepted for publication if the Authors address the following points in the revised manuscript.
Major Issues
1. Although I understand the contribution of the present study to the current literature, I cannot see the significance and the research objectives of the present work in the manuscript. The Authors should emphasize the innovation of their work throughout the manuscript. The last paragraph of the Introduction section should be enriched towards this end.
2. What about the turbulent characteristics? Do the Authors use a turbulence closure model?
3. What are the criteria for the choice of the time step value? How do the Authors achieve the balance between computation efficiency and stability? Does the model take into account stability criteria (e.g. the CFL criterion)?
4. What are the boundary conditions for the velocities? Is it no-slip condition on the walls? What about the top boundary? And also what are the boundary conditions for the Poisson equation?
5. Please use larger font in almost all Figures. It is not clear.
6. The manuscript is generally well written, but there are some grammar and spelling mistakes which should be corrected. I strongly advise a careful review.
Minor Issues
7. Some results and conclusions should be added in the Abstract.
8. Since abbreviations like VOF, VOS, 3D etc. are defined, they should be used more often throughout the manuscript.
9. In Equation (2), which pressure is this? To my understanding it is the total pressure, meaning the sum of dynamic and hydrostatic.
10. Please choose one type of writing when referring to a Figure in the text. As it is now, three types are used (Figure, figure and Fig). Please follow the journal instructions.
11. Please choose one type of writing for volume fraction. Both φ (most times) and f (line 218) are used.
12. Line 235 is step 5 in the iterative procedure. Please add the numbering.
13. In Figure 2 (left images) a volume of 0.4 m×0.61m×0.3m is presented. Is that correct? Does 0.3m correspond to the vertical direction? If so, the axes are not in scale. This should be mentioned.
14. In Figure 2a the configuration of the vertical rectangular object does not seem to match between the left and the right image. It seems rotated by 90 degrees.
15. In Figure 5 I notice a small underestimation of the numerical results and probably a phase-lag. I would like a discussion on this.
16. In Figure 6, the negative minimum force appears at about 1.35 sec, not at 1.7 sec.
17. In Figure 6, where exactly is the impact force measured? Is it at the location (0.754, 0, 0.026) which is mentioned above?
18. In line 485, please define LABSWE (lattice Boltzmann method for shallow water equations).
19. In Figure 12, the caption needs to be enriched. The Figure presents a comparison between two numerical models (the present and the LABSWE).
20. In Figure 13, the vectors are not clear. Maybe less and larger vectors would be better.
21. In Figure 15 the slope Sx is mentioned, but it is not defined in the text.
22. The caption of Figures 16 and 17 is the same. Please add the difference between the 2 cases.
Author Response
Please find the attached file.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Please see the attached word file.
Comments for author File: Comments.pdf
Author Response
Please find the attached file.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I would like to thank the Authors for addressing all my comments and providing a point to point response. Their response is quite detailed and comprehensive, and the quality of the revised manuscript has improved considerably. I am quite satisfied with the revised version and the additions of the Authors.
I suggest that the manuscript is accepted in its present form, just take into consideration the following minor comments.
1) It should be mentioned in the manuscript that Direct Numerical Simulation (DNS) is used.
2) Change Fig. to Figure in page 4 (after equation 19).
3) A quick check for typos etc.
Author Response
Dear Reviewer,
The authors went through the article to correct the typos errors, English grammar, and adding appropriate sentences.
Reviewer 2 Report
Dear authors,
thank you for the additional information (e.g. figures) and clarifications. Please check for any remaining typos before the publication.
Also, in the introduction where you say "Istrati and Buckle [9] established an implicit incompressible FEM-based..." it would be better to say "Istrati and Buckle [9] calibrated and validated an implicit incompressible FEM-based...". Please update this sentence and any typos (e.g. say 'hydrostatic' instead of 'hydrostatical') during the proofreading phase.
Author Response
Dear Reviewer,
The suggestions given by the reviewer has been corrected.
