Review Reports - Numerical Simulation and Engineering Application of a Dovetail-Shaped Bucket

Round 1

Reviewer 1 Report

Some general comments:

Experimental set-up, please indicate the scale of the physical model. I asume Froude similarity is used, but please state it.

Dimensions of the scale model in figure 2 are not indicated

Authors indicate the expressions to calculate discharge coefficients (eqs 2 and 3) but they do not talk about the values found using these expressions, are the range of variation with discharge of these coefficients

Concerning the boundaty conditions I see the upstream one, a pressure entrance and then the flow becomes free surface before falling, but I would like to see more dicussion about the downstrem boundary conditions. Pressure flow is the only option or user can choose another outflow condition depending of the sub or supercritical conditions?

I do not see the mesh size characteristics of the simulation. Another relevant point for Flow3D users is CPU time needed to simulate the time horizon. This should be stated in the document

The last part of the manuscript relates to the simulation of the prototype, the Shiziya reservoir, but there is no link with the physical model. A comparison of water levels and velocities along the tongue and the dissipation element would be of interest, so this should be included in the paper.

Author Response

Response to Reviewer 1 Comments

Point 1: Experimental set-up, please indicate the scale of the physical model. I assume Froude similarity is used, but please state it  

Response 1: The physical model experiment in this paper is a simplified experiment. The model was designed with the Froude similarity, and the scale was 50:1. This revision has been made clear in the section 2.2 from line 103 to line 106.

Point 2: Dimensions of the scale model in figure 2 are not indicated

Response 2: The figure 2 is the schematic diagram of the experimental device. because some equipment is below the laboratory, the specific size of the experimental equipment cannot be obtained. We have made some adjustments to the figure 2 according to reviewer’s requirements.

Point 3: Authors indicate the expressions to calculate discharge coefficients (eqs 2 and 3) but they do not talk about the values found using these expressions, are the range of variation with discharge of these coefficients.

Response 3: In this experiment, rectangular sharp-crested weir with equal width was used to measure the flow rate, the formulas 2 and 3 in the original text were used to calculated the flow rate of the sharp-crested, according to the relevant parameters in this study, Bazan formula was used to calculate the flow rate. The original statement is incorrect, and this revision only hold the Bazan formula.

Point 4: Concerning the boundary conditions I see the upstream one, a pressure entrance and then the flow becomes free surface before falling, but I would like to see more discussion about the downstream boundary conditions. Pressure flow is the only option or user can choose another outflow condition depending of the sub or supercritical conditions?.

Response 4: This calculation is open channel flow, the upstream adopts pressure inlet boundary condition (both static pressure and dynamic pressure) according to the water level. As the downstream is subcritical flow, it is given the boundary of the pressure outlet (only the static pressure distribution is given) according to the water level of the downstream. If the downstream is supercritical, only the outlet boundary condition can be given, the pressure boundary condition is not suitable.

Point 5: I do not see the mesh size characteristics of the simulation. Another relevant point for Flow3D users is CPU time needed to simulate the time horizon. This should be stated in the document.  

Response 5: This revision has supplemented the content about grid size division in the section 2.3. when we use the Flow3D to simulate the model, the 5.04 million of grid uses about 860 CPU hours; the 7.02 million of grid uses about 1200 CPU hours; the 9.37 million of grid uses about 1600 CPU hours, comprehensive consideration of computer operation and computing efficiency, we choose a reasonable computing scheme.

Point 6: The last part of the manuscript relates to the simulation of the prototype, the Shiziya reservoir, but there is no link with the physical model. A comparison of water levels and velocities along the tongue and the dissipation element would be of interest, so this should be included in the paper.  

Response 6: As mentioned above, the physical model test in this study is a simplified model test, the purpose of the test is to verify the accuracy of the numerical model simulation method in simulating the air water tongue problem with complex overhanging flow. Therefore, the specific sizes of the whole overflow dam and swallowtail are not completely corresponding to the actual ShiZiYa reservoir, so it is impossible to compare with. In addition, the focuses of this paper is on the opening air water tongue and the downstream water entry process. Due to the limited space, it does not focus on analyzing the flow velocity.

Modification have been displayed in red font in the text.

We appreciate for editors and reviewers’ warm work earnestly, and hope that the correction will meet with approval.

Once again, thank you very much for your comments and suggestions.

Yours

Sincerely

Guodong LI, Xingnan Li, Jian Ning and Yabing Deng

Author Response File: Author Response.doc

Reviewer 2 Report

In the present paper the authors are presenting results based on a numerical simulation of a dovetail-shaped bucket. The research is interesting but requires major revision. My main concern is about scientific originality and added value. Below are comments/suggestions to the authors.

-Please in the Introduction provide information of what is new and original in this research. Also, please explain the scientific contribution and added value with this paper.

-Please proofread the paper (eg line 12). Editorial and grammatical errors exist.

-Figures are not clear to red. (eg fig1, 2,7, 14)

-Derails about the development of the numerical model are required. Softwares cannot be used as black boxes in scientific research. Please provide all required information of how you build the model, equations that are solved but also methods for solving the equation of motion. How all the boundaries are modelled numerically? Provide information about the flow (compressible or incompressible and how this is numerically treated).

-Live 185; please explain what is the 7 million grid number and also provide a convergence study about why did you choose this number and not eg 5 million or 20 million. Is the 7 million number capable for solving the huge domain?

Author Response

Response to Reviewer 2 Comments

Point 1: Please in the Introduction provide information of what is new and original in this research. Also, please explain the scientific contribution and added value with this paper.

Response 1: The innovation and the value of the study have been supplemented and modified in the Introduction. Dovetail-shaped bucket is a new type of overhanging bucket, which can solve the problem of the longitudinal stretching of water tongue. In this paper, a numerical simulation model of jet water through dovetail-shaped bucket is given based on a three-dimensional CFD, and this model is also applied to the optimization of flood discharge scheme for practical engineering problems. It is of great significance to fully understand the flow characteristics of the shape of the bucket and solve practical engineering problems.

Point 2: Please proofread the paper (eg line 12). Editorial and grammatical errors exist.

Response 2: According to the reviewer’s comment, we have corrected this sentence.

Point 3: Figures are not clear to read. (eg fig1, 2,7, 14)

Response 3: The Figures 1,2,7,14 have been modified in the text

Point 4: Details about the development of the numerical model are required. Software cannot be used as black boxes in scientific research. Please provide all required information of how you build the model, equations that are solved but also methods for solving the equation of motion. How all the boundaries are modelled numerically? Provide information about the flow (compressible or incompressible and how this is numerically treated).

Response 4: In the modification, the model building, equation solving method, free surface, boundary condition setting and so on has been supplemented and modified in the section 2.1.

Point 5: Live 185; please explain what is the 7 million grid number and also provide a convergence study about why did you choose this number and not eg 5 million or 20 million. Is the 7 million number capable for solving the huge domain?

Response 5: the mesh division scheme and mesh convergence have been modified in this revised manuscript in the section 2.3.