Study on the Effect of Hull Attitude on the Resistance Reduction of SWATH with Airflow Injection

Round 1

Reviewer 1 Report

General Comments:

In the manuscript, author(s) study the influence of the hull attitude of a SWATH on the air coverage and resistance reduction using the air lubrication method. The resistance of the SWATH under different trim angles and drafts and drag reduction rates are investigated. RANS and VOF methods are employed to establish/simulate the numerical model. The mathematical model is validated against experimental results. The research idea is original and presents promising outcomes in terms of the characterization resistance reduction using the air lubrication method. I believe that the research contributes to the current literature positively. The research design is appropriate, but it must be improved. The manuscript organization is good. The introduction section provides sufficient information from the literature. In my humble opinion, the quality of paper may be increased further if the points below are considered/corrected. 

 

Specific Comments:

- Typo in the abstract of the manuscript: SWATCH --> SWATH

- Show readers the long form of SWATH abbr. as SWATH (small waterplane area twin hull) when you first use this abbr.

- In section 2.1, show readers the long form of "URANS" abbr. 

*Numerical Solution details are missing and/or very superficial:

*It is reported that the free surface is modelled using VOF method; however, it is not reported which numerical technique is utilized to discretize the computational domain.

*How are the convection and diffusion terms in the governing equations treated? 

*Please add details regarding your simulation details because these outcomes should be reproducible. 

-In section 3.2, why is sqrt (2) used as a scaling factor to obtain the Fine, Medium, and Coarse meshes? *Why are these mesh densities selected during the grid independence study?

*What are the criteria considered to select a certain grid size in the computational domain and to refine locally?

*Please define/explain all the terms in this section. All the terms used in pg. 5 and in the entire manuscript should be defined or explained.

-The use of the model(s) should be discussed for further studies.

-Please add a paragraph to discuss what novelty this research presents to the current literature and how the outcomes of this study affect future designs.  

-Conclusions may be expanded with outcomes (outcomes may be reported as numbers or percentages) and model limitations. 

-Manuscript also requires a minor spell check for typos. 

 

Thanks    

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript discusses the application of the air lubrication method to the SWATH (small waterplane area twin hull) for the purpose of reducing resistance. And investigated how the trim angle and draft impact drag reduction, comparing computed results with actual test outcomes and conducting a grid independence test.  The manuscript provides a clear overview of the paper's focus and methodology. However, there are a few areas where more detail or clarity could be beneficial:

1. It might help to briefly explain why reducing resistance is important. Is it to improve efficiency, speed, or fuel consumption? Providing this context can make the purpose clearer to readers who might not be familiar with the topic.

2. You've mentioned applying the air lubrication method, but it might be useful to briefly explain what this method involves. 

3. While you've outlined the general process of investigation, adding a bit more detail about the specific methods used for computation, simulation, and testing could enhance the manuscript's comprehensiveness.

4. Consider adding a sentence about the significance of the findings. How might the results of this study contribute to the field of naval architecture or engineering?

5. Overall, the manuscript provides a good introduction to the paper's content. Expanding a bit on the methods used, offering context, and clarifying certain points could enhance its readability and effectiveness.

English needs to be revised.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

The authors performed an interesting study to decrease the fuel consumption of ships considering the air lubrication method. They developed a numerical model and made some simulations to observe the effect of trim and draft. Before it is considered for publication, the following comments should be addressed:

-I recommend emphasizing the novelties and contributions of the analysis by quantitative results in the abstract.

-The authors can benefit from these studies: https://doi.org/10.1016/j.trd.2020.102389

https://www.taylorfrancis.com/chapters/edit/10.1201/9781003320289-5

-Relevant papers are presented in general forms. Please mention them in more detail. For instance, what are the main results of "Mäkiharju [8]"? Then, explain comparatively the available approaches and define the gap based on the information learned from the literature. 

-In the introduction, the strengths, main contributions, and novelties of the study compared to both previous study of authors and relevant papers should be explained more clearly. 

-Figure and its name should be given in the same page. Please check Figs 7 and 9. 

-Please eliminate typos. (Check the lines after section 4.2 and also all parts of the paper)

-I suggest giving Table 6 on a page.

-Please elaborate and add limitations of the paper and assumptions for the analysis. 

Minor editing of English language required

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Thanks for the revision.

In the abstract, "SWACH" needs to be corrected as "SWATH".

Author Response

It has been corrected.

Thank you for your review.