Review Reports

Round 1

Reviewer 1 Report

In general, the paper is good and is interesting, but it requires a major revision. There are some recommendations.

I recommend the authors to highlight the corrections and changes in the manuscript before the paper will undergo further assessment.

Therefore, the authors should revise the article by taking into consideration the following comments.

• Authors should explain more about the novelty of their work in the introduction.

• A lot of the introduction-related material is very forced, poorly articulated, and lacking a succinct structure. I would encourage the authors to consider consulting the article by George M. Whitesides, which was titled “Whitesides’ Group: Writing a Paper” such that the questions posed to the reader could be answered when reorganizing and redrafting a new introduction. Primarily, consider the following and outline your introduction (after rewriting your results and discussion sections) accordingly…
• “Why did I do the work?”
• “What were the central motivations and hypotheses?”
• „What are the objectives of this work?“
• “Why is the work important?”
• “Who else has done what? How? What have we done previously?”
• “What should the reader watch for in the paper?”
• “What are the interesting high points?”
• “What strategy did we use?”
• “What should the reader expect as conclusion?”
• In results and discussion, the authors should discuss on their results deeply. I strongly recommend expanding: Introduction, Conclusions and the Results sections. The aim should be to: 1) give a broader view of the literature on the topic and the current state-of-the-art; 2) clarify and discuss the novelty and the significance of the results obtained here, and compare them with those available in the literature, also including discussions on potential applications; 3) complete the manuscript with some additional, less basic results; 4) The authors should show the comparison between their results and previous works.
• The authors must provide a greater discussion of the results.
• The conclusions should be re-written, they should be specific and should not include as the initial paragraphs, which seems a summary, it must be enriched about discussion on solving problem.
• The quality of the figures, for example Figure 9 in this document needs to be improved; the figures need to be larger in size so the data and labels can be clearly read. Figure 7 is very confusing, Table 2 is too large, what abou to split it?
• The declared equations from (1) to (5) are general. What is your unique and original new contribution in this area? I am looking forward to receive the revised version of this manuscript

Author Response

Thank you for your guidance. I tried my best to modify part of the content, especially the conclusion! 

Author Response File: Author Response.pdf

Reviewer 2 Report

The current paper pertains to an interesting topic, which has also a practical value. Namely, a numerical analysis of abrasive flow polishing nozzle surface with magnetic particles is presented. Although conceptually, it has a certain level of novelty and some interesting results and conclusions can be deduced, there are some points that have to be significantly improved before it can be accepted for publication.
More specifically:
•    equation 3 is not according to the journal's template.
•    it is stated: "For the solid-liquid two-phase magnetic fluid polishing liquid, the Mixture model is selected.". Please provide the exact formula.
•    authors state:"...so the inlet condition is set as the velocity inlet, and the direction is perpendicular to the entrance boundary;". At the same time, in line 208, it is also stated that D is the inlet pressure, which also is considered as a study parameter. As far of my knowledge, and since the outlet pressure was defined equal to atmospheric pressure, the inlet boundary condition must be either the inlet velocity, or the inlet pressure. Here, although in Table 1 it is referred as varying parameter the inlet pressure, it is previously stated that as boundary condition the respective velocity was defined. Please clarify. 
•    In Table 1 the abrasive particle size is considered as a study parameter. Nevertheless, there is no clear reference how the abrasive particle size affects the model implementation, and where the particle size is incorporated into the model's equations.
•    please provide all the model's governing equations in details (e.g. the Navier Stokes)
•    Figure 7 does not provide any clear conclusions since the areas where the shear forces are different are not clearly presented, and hence, all the presented results  are macroscopically the same and only differ in the scale.
•    some more details regarding the surface roughness measuring methodology are absolutely necessary.
•    A statistical analysis (ANOVA) of the experimental and numerical results are absolutely necessary. Else, the deduced conclusions regarding the significance of each parameter seems arbitrary.
•    Based on the deduced conclusions, the particle size and the magnetic field does not significantly influence the process' result. Authors have to give a reasonable explanation and support these conclusions with some relevant literature.
•    does the shear stress has a clear relation with the obtained roughness? It would be interesting if authors discuss it, and if they propose a possible correlation model. Else, the numerical data do not hold any additional value.
•    an overall improvement in syntax and grammar is suggested.

Considering the aforementioned, in my humble opinion, the current paper cannot be accepted before a major revision.

Author Response

Thank you for your guidance. I tried my best to modify part of the content, especially the conclusion! 

Author Response File: Author Response.docx

Reviewer 3 Report

The manuscript entitled "Numerical analysis of abrasive flow polishing nozzle surface with magnetic particles" presents a finishing method combining abrasive flow machining and magnetorheological machining. Although the subject of the paper is interesting, the presentation of results is generally not very appropriate and necessary information is missing from various parts of the paper. Thus, it is required that the authors performed radical modifications to their manuscript before it can be considered for publication.

At first, the title of the manuscript is not totally appropriate, as the paper does not mainly involve a numerical model but an experiment as well. Moreover, the type of the nozzle should be mentioned as well as the particular machining process involved. Thus, the title should be changed in an appropriate way e.g. "Experimental and numerical analysis of magnetic particles assisted abrasive flow polishing of fuel injection nozzles".

In the abstract section, the pre-last sentence should end with a period "."

In the Introduction section, at the first paragraph the authors should mention which type of type of engines is relevant to the studied nozzle and mention also the specific type of nozzle. In line 33, "polished" should be changed to "polishing". Special attention should be paid on correct grammar, as especially in the first paragraph the word "taked" is repeated multiple times instead of "took" and also some other verbs should be used in past tense instead of present tense.

Regarding the references to previous works, the number of the reference should be placed after "et al." and not before it. In line 76, instead of "," a period should be used to complete the sentence "in a magnetic field." and the next sentence should begin with a capital letter. In general, the description of previous works should be more concise instead of mentioning a lot of details about each work. In the pre-last paragraph of the Introduction, the authors state that there are not many works on solid-liquid two-phase magnetic fluid precision polishing. However, this is not clear from the literature review. Thus they should present more relevant works and rephrase the existing paragraphs where it is needed in order to clarify their novelty.

In line 127, a verb should be added in the phrase "it quickly through", e.g. "it passes quickly through". Moreover, the phrase "drive abrasive clamping workpiece surface" should be properly corrected in order to be more comprehensible. The first letter of the first word of the title of each section and subsection should be capitalized. Equation 3 should be more properly placed in the text. The last paragraph of section 2, beginning from "The tetrahedron ..." should be rephrased with more appropriate terms and more details.

In section 3, it is required that an appropriate introductory section be added at the beginning.  An appropriate schematic of the computational model, including the boundary conditions should be added. Moreover, all the equations solved should be presented, both for the fluid flow and magnetic field as well as their coupling and material properties should be presented in form of a Table. The authors seem to include the effect of particles as a fluid phase, but this should be properly stated and justified. 

In subsection 3.1, the authors should include an additional paragraph describing the examined nozzle, giving details about its use, the specific conditions occurring when it is being used and the requirements of its manufacturing. Furthermore, they should present an additional schematic relating their model to the actual device used for this process, which was depicted in Figure 1. Figure 5 should be enlarged in order to be able to observe its quality clearly. The authors state that grid quality was over 0.3, which is acceptable but in fact the quality should be as close as possible to 1. They should provide more details about the type of finite volumes used, their number, the quality metrics used and their values and present a mesh independence diagram in order to prove that their mesh quality is appropriate. Thus, instead of Figure 6, a more detailed table should be used regarding mesh quality metrics.  

Subsection 3.2 is generally inappropriately presented. Various modifications are required by the authors in order to present their results in a more comprehensive way. At first, they should mention which orthogonal array was used, probably L16. The parameter "voltage strength of electromagnet" should be properly explained and the relevant magnetic field value in each case should be mentioned. How was kinematic viscosity changed? If different fluids are tested, they should be mentioned. How were the values of inlet pressure selected? How can the mesh size be incorporated into the model? 

In figure 7, the authors should enlarge the areas where the high shear stress values occur in each image, otherwise, all images seem identical, with only the values of the colorbar changing. Table 2 as well as the two following paragraphs should be omitted from the text and instead the authors should present the main effects plot regarding each important output of their simulation with correct units, analyze and discuss them appropriately e.g. by using ANOVA method.  The explanations should be based on simulation results.

In section 4, line 293 the authors state that various additives are used. They should mention these additives in more details. A suitable schematic and photo of the experimental device and setup which were used should be provided. In subsection 4.3 the authors should add a schematic depicting the positions in which the measurements with the optical microscope were conducted. Moreover, main effects and ANOVA should be presented for the experimental results of surface roughness in order to analyze the obtained results more clearly.

In the conclusion section, it is not appropriate to number the paragraphs as 5.1, 5.2 etc. The first two paragraphs should be rephrased in order to contain more relevant information and be more detailed.

Author Response

Thank you for your guidance. I tried my best to modify part of the content, especially the conclusion! 

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

I am afraid that the current paper was not revised adequately and according to the review suggestions and comments. Important issues like the model's governing equations, and the mixture model that were utilized and solved in simulations still are not presented in details. Moreover, the Figure 7 results still do not provide any practical information or conclusions. Finally, the ANOVA was not performed properly by presenting the Main Effects Plots and the Interaction Plots, and hence, the discussion and conclusion sections are significantly weak. Thus, in my opinion, the current paper cannot be accepted for publication.

Author Response

Dear, experts  

Thank you for pointing out the problem. I have supplemented the knowledge Of DOE（Design Of Experiment）,  Please give me your valuable advice again.  

The problem  

1. I added the effect of magnetic field force into the governing equation of the model, and the wall shear force cloud picture did differ from the numerical analysis. I have found the reason, and the numerical simulation modeling equation is correct.  

The problem  

2. I introduced the standard least square method to re-analyze the data.  

Your student,

Liu Guosong  

Author Response File: Author Response.docx

Reviewer 3 Report

The authors did not conduct most of the proposed modifications, except for some minor corrections mainly in the Abstract and Introduction sections. The figures and discussion of the findings were almost not altered. Moreover, some of the corrections  contain errors and some others are not improving the quality of the original manuscript. Thus, this paper cannot be accepted for publication.

 

the authors did not provide any document regarding the responses to the reviewer, which is required by the journal in order to answer the reviewer's comments one by one. The document which was uploaded contained only the revised manuscript.

Thus, my opinion was that this paper cannot be acceptable for publication given that a lot of crucial information about the models is missing and the analysis of the results was not conducted appropriately. My comment regarding the errors in the corrections is relevant to the conclusion section, which is not representative of the main findings of the manuscript and several language errors which still exist in the manuscript. However, apart from minor corrections, the main parts of the manuscript contained no serious modification.

Author Response

Dear, professor  

Thank you for pointing out the problem. I have supplemented the knowledge Of DOE（Design Of Experiment）,  Please give me your valuable advice again.  

1.I added the effect of magnetic field force into the governing equation of the model, and the wall shear force cloud picture did differ from the numerical analysis. I have found the reason, and the numerical simulation modeling equation is correct.  

2.I introduced the standard least square method to re-analyze the data.  

3.If the content of the article can pass, I will revise the language expression again.

Your student,

Liu Guosong  

Author Response File: Author Response.docx

Round 3

Reviewer 2 Report

The authors have significantly improve the manuscript according to the review comments and suggestions, thus, in my humble opinion, the current paper can be accepted. Nevertheless, there are some typos that have to be corrected, along with some editing issues.

Author Response

Dear expert,

     Thank you for your guidance for many times. I have hired an English editor to help revise the draft. Please check.

Author Response File: Author Response.pdf

Reviewer 3 Report

The authors have not performed substantial changes to their manuscript as it was suggested to them previously, especially regarding the description of their model and the presentation and discussion of the results. Thus, the article cannot be accepted in its current form.

Author Response

Dear expert,

     Thank you for your guidance for many times. Under your advice, I re-analyzed the experimental data with the method of factor analysis, and found that the numerical analysis of Fluent was inconsistent with the simulation result. The main reason is the inherent module of Fluent, which lacks accurate mathematical logic.  I think the conclusion of this paper is drawn under your guidance and has its special value.

     Thank you very much!  

Author Response File: Author Response.pdf