Three-Dimensional Hydrodynamic Analysis of a Flexible Caudal Fin

Round 1

Reviewer 1 Report

Review of the manuscript by Khin and Obi

Three-Dimensional Hydrodynamic Analysis of a Flexible Caudal Fin

Submitted to Applied Sciences (2048695)

GENERAL COMMENTS

The paper deals with the three-dimensional hydrodynamic analysis of a flexible caudal fin by using a 3D fluid-structure coupled simulation. A plate immersed in a water tank is adopted vertically by its leading edge, and some parametric studies are presented. Many interesting dynamic behaviors are observed, and the numerical results could be used to provide new guidelines for the design of robotic underwater vehicles. Good quantitative agreements could be found between the calculated and experimental results for the trailing edge amplitude of the caudal fin and the phase lag of the trailing edge relative to the leading edge. According to the high-quality standards of the Applied Sciences, the paper can be considered for publication after some revisions. Some major and minor comments are summarized as follows.

MAJOR/MINOR COMMENTS

u  The INTRODUCTION is essentially a disordered list of concise (sometimes vague and imprecise) statements about what other authors did in the past in the field. The mere sum of these statements is far from a coherent analysis of the current state of the art and certainly does not suffice to support the paper’s motivations. The authors must relate the referenced works to each other by highlighting the advancements and significant theoretical/applied results of each piece of research. The motivation of the manuscript should be illustrated more clearly and concisely.

u  As to the schematic view of the model, I wonder how to choose the size of fluid domain.

u  The experimental and simulation procedures and results should be illustrated more specifically.

u  In the hydrodynamic analysis, there are many hydrodynamic parameters. The vibration characteristics are closely related to these parameters. More illustrations should be added here, and some parameters and coefficients should be explained more clearly.

u  The innovation and creativity should be illustrated more clearly in the Conclusion. It seems that some conclusions are not new, and it is too wordy.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Manuscript ID: applsci-2048695

Title: Three-Dimensional Hydrodynamic Analysis of a Flexible Caudal Fin

In this study, the flow field of the basic model of a square flexible flapping plate was investigated, numerically. The open-source CFD software OpenFOAM is utilized for this simulation. The validation test and mesh grid study are done. The following major and minor comments should be addressed by the authors before the final decision:  

 ·         The novelty of the study should be highlighted in more detail. The geometry of the problem is so simple.

·         Graphs in Fig. 3 have no legend!

·         In section 3.1., the mesh size must be doubled in each step (compared to the previous state). In this case, the common points between two grids of different sizes are recognizable and the comparison is more meaningful.

·         The following review and research papers related to FSI problems of fixed and flexible boundaries are missing in the literature review:             10.4208/cicp.RE-2022-0041; 10.1016/j.molliq.2020.114941

·         Enrich the abstract and conclusion sections with more quantitative data from the research.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

All the comments are addressed.