Full Three-Dimensional Inverse Design Method for S-Ducts Using a New Dimensionless Flow Parameter
Round 1
Reviewer 1 Report
The authors present an inverse design methodology for the design of S-ducts.
The abstract is not complete in terms of referring to the benefits of the proposed methodology. For example, it reduces the computational cost, better efficiency can be achieved, the physical mechanisms are better understood, etc.
In the Introduction and reference to the background work, some attention should be given to the direct optimisation design studies on S-ducts, such as Zachos et al., D' Ambros et al., etc.
Even though the authors describe and emphasise the complexitied of the flow through a S-duct, they deploy an inviscid flow solver in their methodology. This certainly won't capture all the critical flow phenomena. Hence, the design search will be misled. The authors need to justify the choice of their flow solver algorithm.
In Figure 6, is the highlighted 'divergence area' of concern in the proposed method? In the following section, the authors proposed an enhanced method, but they do not present the results in the same fashion in order to be able to directly compare and appreciate the improvements to the accuracy of their method. This should be clarified in the manuscript.
In Section 4 the authors refer to a viscous flow solver. Which one? Is it an in-house code? Is an appropriate reference available? In any case, it is a RANS approach, which is shown in the literature that cannot fully capture the flow details. This should be mentioned in the manuscript.
Also, the comparisons presented in Table 2, should be validated with higher fidelity CFD.
A reference and comparison to improvements in S-duct design should be mentioned. Again, check the work by Zachos et al, and D' Ambros et al. among others in the literature.
The references are rather outdated. The most recent journal paper, in 2018, refers to wing design, which is not directly relevant to the core of the proposed methodology or application (i.e. the design of S-ducts). There is only a reference from 2020 published by the same research team.
This is a very interesting topic. I would strongly recommend the authors to consider the points above and resubmit.
Author Response
Please see attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This is an interesting topic, but the paper structure and english grammar needs improvement before it can be considered for publication.
The structure of the paper needs to be improved so that the novelty of the paper becomes more apparent. Writing style needs to be more engaging.
Don't lump references, discuss each individually
Improve the quality of the references and use more current references. There are only 8 of 45 references that are less than 5 years old.
English grammar needs improvement (i.e proper tense, excessive number of consecutive sentences starting with the same word, etc.). Proper structure of a sentence when using a variable
Justify grid size.
Grid should be fine near the wall
Discuss what is occuring at different locations in the structure.
Are all the cross sections the same area?
Are all the variables defined?
Figure title should be more descriptive. Some figures need a dimension
Discussion of figures and tables should be more detailed.
--define pup and pdown
There may be an excessive number of figures, are all important.
Might need a location where slices are taken in the figure
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have addressed all the raised points.
Reviewer 2 Report
The concerns of the reviewer have been addressed
