Numerical Simulation of Free Surface Flow on Spillways and Channel Chutes with Wall and Step Abutments by Coupling Turbulence and Air Entrainment Models

Round 1

Reviewer 1 Report

The paper presents some interesting results, thus it deserves eventual publication.  The work is based on numerical simulations based on commercial software, and as such the results are inherently weak.  Since the authors do not have access to the source code, it is impossible to discern what part of the differences in the comparisons is real and what is a potential flaw in the code.  There is only one way around this dilemma: Carry out comparisons of the turbulence models and aeration effects for simple cases for which validation is possible by comparisons to DNS results, analytical solutions of experimental measurements in controlled environments.  Once that is established, the reader can begin to trust the results presented in this paper. Otherwise, the value of the present paper will be limited to customers of the subject commercial package who have no other means of numerical modeling. 

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 2 Report

In the presented paper the Flow 3D fluid computation software with both Renormalization group turbulence (RNG) and Large Eddy Simulation (LES) models and air entrainment one is applied for simulations of the free surface flow through the spillway, channel chute and stirling basin of the Ngan Truoi spillway to adjust two abutments.

 The numerical outputs provided water level, velocity, pressure, verified by experimental data to estimate the influence of grid size as well as turbulent model types. The paper also points out the need to add air entrainment model in simulating rapid flow over group of hydraulic construction.

The paper is very interesting. I only suggest to specify the differences of the computational times required for the different simulation scenarios (e.g., different results of pressure, velocity with /without air, with LES., … in figures 14, or 17).

Author Response

Specify the differences of the computational times required for the different simulation scenarios (e.g., different results of pressure, velocity with /without air, with LES., … in figures 14, or 17).

Author's reply.

• In our study, 3 models were used to obtain numerical result in Figure 14 and 17.
• Model a) Turbulent RANs model + with air entrainment model: computational time is 7h56mins
• Model b) Turbulent RANs model + without air entrainment model: computational time is 7h24mins
• Model c) Turbulent LES model + air entrainment model: computational time is 7h21mins

Round 2

Reviewer 1 Report

The authors have answered my questions, so I agree with publication.