The Estimation of Trapped Modes in a Cavity–Duct Waveguide Based on the Coupling of Acoustic and Flow Fields

Round 1

Reviewer 1 Report

The authors numerically studied the trapped acoustic modes in the cavity-duct waveguide with CAA and CFD tools. Different types of mode around the cavity are displayed, and the influences of Mach number and the size of cavity on trapped modes are also studied and the trend trapped mode frequency is revealed. The manuscript should be improved essentially before being considered to be published.

The major drawback of the manuscript is that no analysis of the coupling mechanism of the acoustic and flow fields was offered. Rather, the authors only present some superficial results are listed.

The authors should present the detailed information of mesh information of the numerical model and the mesh independence checking procedure. No CFD results can be found in the manuscript.

Are the physical quantities all non-dimensional? No units of the frequency and pressure can be found throughout the manuscript.

L165 the physical interpretation of A, B, x, y, f, g should be presented.

Figures 2, 3 and 5 are of different sections? If the authors want to comparing them, they should be at the same cross section.

There are lots of grammar and spelling mistakes. For examples, L135 CFDc->CFD; L220-L222; L239 developped-> developed; L245 Further more-> Furthermore.

Author Response

Dear Reviewer: 
Thank you very much for your constructive comments that have helped us to improve the manuscript. The point-by-point reply is attached.

Author Response File: Author Response.pdf

Reviewer 2 Report

The topic is quite interesting. Hoewever, the presentation of the paper is not good, in particular, concerning the used method and the literature survey. My recommendation is major revision. Below are my comments:

 

1. The reference (i.e. Citation) is very limited. As a results, the state of the art of the manuscript is lacking. In fact, only 2 from 14 references is up-to-date. The authors must add the recent citations (< 5 last year) to give the reader the novelty of the research.

 

2. The description of the problem formulation is very lacking. For example, the dimension of the computational domain as shown in Fig. 1 is missing. Please add it.

 

3. How of the authors define the parameter "D" to calculate the Reynolds number is unclear. Please give more detail definition

 

4. The nomenclature is missing. Please add it.

 

5. Please define the normalized parameters, such as dimensionless frequency, pressure, atc

 

6. The reason of why the authors employed two modes f = 0.394 and 0.445 is unclear. Please add the discussion dealing with this issue.

 

7. Line 240. The authors claimed that in the previous section, the Euler equation is adopted, not NS Eq. Which is correct, NS or Euler?

 

8. The discussion dealing with the point of why the increase in Mach number can affect the frequency is missing. Please add it.

 

9. It is stronlgy suggested for authors to discuss and compare their findings with the available literature to justify  the accuracy in terms of the methods and the data (i.e. Results).

Author Response

Dear Reviewer: 
Thank you very much for your constructive comments that have helped us to improve the manuscript. The point-by-point reply to your comments is attached.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors made a major improvement following the reviewer's remarks. Now, it can be accepted for publication