Effect of the Marangoni Convection in the Unsteady Thin Film Spray of CNT Nanofluids
, Safyan Mukhtar 3, Fawad Hussain 4, Kottakkaran Sooppy Nisar 5 and Poom Kumam 6,7,8,*Round 1
Reviewer 1 Report
This is the review of the paper “Effect of the Marangoni Convection in the Unsteady 2 Thin Film Spray of CNTs Nanofluid” by Rehman et al. It deals with the numerical study of the effect of Marangoni convection on the thin film spray of two kinds of CNT-based nanofluids on a cylinder. The work has clear applications. However, the paper needs to be checked at several places for more clarity and better explanation. The remarks are put next.
- The authors should check the use of the definite article “the”. Very often, it should be the undefinite one “a” or no article at all.
- In overall the English language should be checked.
- Line 93 through 95, the density, viscosity, heat capacity and thermal conductivity are rather the ones of the nanofluid and not of the solid particles.
- Also, in section the explanation in section 2 of the Marangoni influence should be put much more explicitly and elaborated a bit more. This is not clear in this section.
- Some more literature research should be performed on especially the nanofluid viscosity (the authors can use: Journal of Non-Newtonian Fluid Mechanics, Volume 253, Pages 1-6) and the thermal conductivity of CNT on the different works proposed (the authors can use: International Journal of Nanoscience, Volume 13, Article number 1450022; Physica E: Low-Dimensional Systems and Nanostructures, Volume 71, Pages 117-122). After that, the authors should justify why they chose the ones in their paper.
- The first phrase of the abstract is not clear. It should be rewritten.
- It would be better to put Tables 1 to 3 before the figures.
- What do the authors mean by “The SWCNTs and MWCNTs are clearly visible…” in line 235?
- In line 259: add a space before “The increasing…”
- Line 280: “sufficintly” should be “sufficiently”
- Line 298: do the authors mean “point of inflection” instead of “point of infection”?
Author Response
Processes-488600:
Title: “Effect of the Marangoni Convection in the Unsteady Thin Film Spray of CNTs Nanofluid”
Authors: Ali Rehman1, Taza Gul2*, Zabidin Bin Salleh2, Safyan Mukhtar3, Fawad Hussain4, Poom Kumam5,6,7
Dear Editor,
Thank you for the opportunity to revise our manuscript in accordance with the valuable
comments\ suggestions of reviewers. We incorporate with great care the constructive suggestions of all the reviewers. As a result, the manuscript is substantially improved after making the required changes.
Best Regards
Dr. Taza Gul,
Associate Professor, Department of Mathematics, City University of Science and Information Technology, Peshawar, Pakistan.
Detailed responses of queries and comments of referee’s are given below:
Academic Editor Comments
To facilitate peer review and to approximate the form of the paper to what is commonly adopted by the scientific community, authors need to introduce some changes of form in the manuscript before it can continue to peer review:
1. Figures should be placed just after the position in the text they are mentioned
Author’s Response (1)
Replaced as suggested by the honorable editor.
2. The physical situation being studied needs to be described in the beginning (section 2). So, Figure 1 needs to be described in the first paragraph of the "2. Mathematical formulation". Figures 2 and 3 seem to belong to section "3. Solution by OHAM:" and should be mentioned and described there.
Author’s Response (2)
Replaced as suggested by the honorable editor in the revised manuscript.
3. Check if all variables are defined in the text and consider adding a notation section after the conclusions.
Author’s Response (3)
Nomenclature table for the variables and parameters is added as suggested by the honorable editor in the revised manuscript.
4. The last paragraph of the introduction should describe the present paper (which it seems is what the authors intend). The use of past tense in this paragraph confuses the reader. The present tense should be used instead. For example, instead of "recent study has been focused" it should be "the present study focuses on".
Author’s Response (4)
Rectified as suggested.
Reviver#1:
This is the review of the paper “Effect of the Marangoni Convection in the Unsteady 2 Thin Film Spray of CNTs Nanofluid” by Rehman et al. It deals with the numerical study of the effect of Marangoni convection on the thin film spray of two kinds of CNT-based nanofluids on a cylinder. The work has clear applications. However, the paper needs to be checked at several places for more clarity and better explanation. The remarks are put next.
- The authors should check the use of the definite article “the”. Very often, it should be the undefinite one “a” or no article at all.
- In overall the English language should be checked.
Author’s Response.
Rectified as suggested by the honorable reviewer.
- Line 93 through 95, the density, viscosity, heat capacity and thermal conductivity are rather the ones of the nanofluid and not of the solid particles.
- Also, in section the explanation in section 2 of the Marangoni influence should be put much more explicitly and elaborated a bit more. This is not clear in this section.
Author’s Response.
Rectified as suggested by the honorable reviewer.
- Some more literature research should be performed on especially the nanofluid viscosity (the authors can use: Journal of Non-Newtonian Fluid Mechanics, Volume 253, Pages 1-6) and the thermal conductivity of CNT on the different works proposed (the authors can use: International Journal of Nanoscience, Volume 13, Article number 1450022; Physica E: Low-Dimensional Systems and Nanostructures, Volume 71, Pages 117-122). After that, the authors should justify why they chose the ones in their paper.
- The first phrase of the abstract is not clear. It should be rewritten.
- It would be better to put Tables 1 to 3 before the figures.
- What do the authors mean by “The SWCNTs and MWCNTs are clearly visible…” in line 235?
- In line 259: add a space before “The increasing…”
- Line 280: “sufficintly” should be “sufficiently”
- Line 298: do the authors mean “point of inflection” instead of “point of infection”?
Author’s Response.
Rectified and all the suggested points raised by the honorable reviewer are highlighted in the revised manuscript.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript is not well-written. A wide range of grammatical mistakes and spelling errors are evident in several parts of the manuscript.
Unnecessary words with upper case letter appeared (especially in the literature review, mathematical formulation section)
The illustrations are of poor quality and are in need of explicit captions.
Continuity equation in cylindrical co-ordinate is wrongly represented in Eq 1.
Authors mention that the ‘nf’ signifies solid particles’ physical properties which is wrong.
Equations formatting is very inconsistent.
Authors must rewrite the equation 9.
Authors misrepresented different thermophysical properties.
Authors did not provide the important scaling velocity, temperature and pressure parameters with proper justifications.
The solid volume fraction of the nanofluid of 0.2 is highly impractical.
Units of physical parameters are wrong in the table of thermophysical properties (for example, Cp).
Authors did not provide the necessary grid independence test
Authors did not provide validation of the code.
Author Response
Processes-488600:
Title: “Effect of the Marangoni Convection in the Unsteady Thin Film Spray of CNTs Nanofluid”
Authors: Ali Rehman1, Taza Gul2*, Zabidin Bin Salleh2, Safyan Mukhtar3, Fawad Hussain4, Poom Kumam5,6,7
Dear Editor,
Thank you for the opportunity to revise our manuscript in accordance with the valuable
comments\ suggestions of reviewers. We incorporate with great care the constructive suggestions of all the reviewers. As a result, the manuscript is substantially improved after making the required changes.
Best Regards
Dr. Taza Gul,
Associate Professor, Department of Mathematics, City University of Science and Information Technology, Peshawar, Pakistan.
Detailed responses of queries and comments of referee’s are given below:
Academic Editor Comments
To facilitate peer review and to approximate the form of the paper to what is commonly adopted by the scientific community, authors need to introduce some changes of form in the manuscript before it can continue to peer review:
1. Figures should be placed just after the position in the text they are mentioned
Author’s Response (1)
Replaced as suggested by the honorable editor.
2. The physical situation being studied needs to be described in the beginning (section 2). So, Figure 1 needs to be described in the first paragraph of the "2. Mathematical formulation". Figures 2 and 3 seem to belong to section "3. Solution by OHAM:" and should be mentioned and described there.
Author’s Response (2)
Replaced as suggested by the honorable editor in the revised manuscript.
3. Check if all variables are defined in the text and consider adding a notation section after the conclusions.
Author’s Response (3)
Nomenclature table for the variables and parameters is added as suggested by the honorable editor in the revised manuscript.
4. The last paragraph of the introduction should describe the present paper (which it seems is what the authors intend). The use of past tense in this paragraph confuses the reader. The present tense should be used instead. For example, instead of "recent study has been focused" it should be "the present study focuses on".
Author’s Response (4)
Rectified as suggested.
Reviewer#2
Comments and Suggestions for Authors
The manuscript is not well-written. A wide range of grammatical mistakes and spelling errors are evident in several parts of the manuscript.
Unnecessary words with upper case letter appeared (especially in the literature review, mathematical formulation section)
The illustrations are of poor quality and are in need of explicit captions.
Continuity equation in cylindrical co-ordinate is wrongly represented in Eq 1.
Authors mention that the ‘nf’ signifies solid particles’ physical properties which is wrong.
Equations formatting is very inconsistent.
Authors must rewrite the equation 9.
Author’s Response.
Rectified as suggested by the honorable reviewer.
Authors misrepresented different thermophysical properties.
Authors did not provide the important scaling velocity, temperature and pressure parameters with proper justifications.
The solid volume fraction of the nanofluid of 0.2 is highly impractical.
Author’s Response.
Rectified as suggested by the honorable reviewer.
Units of physical parameters are wrong in the table of thermophysical properties (for example, Cp).
Authors did not provide the necessary grid independence test
Authors did not provide validation of the code.
Author’s Response.
Rectified as suggested by the honorable reviewer and for clarification the published papers are cited in the revised manuscript.
Author Response File: Author Response.pdf
Reviewer 3 Report
Review of the paper titled "Effect of the Marangoni Convection in the Unsteady Thin Film Spray of CNTs Nanofluid" authored by Gul et al. (2019)
The paper focuses on the Marangoni Convection Impacts in the unsteady thin film spray of nanofluid based system (CNT). In this regard, the authors evaluate the effect of the physical parameters as a a function of velocity, pressure and temperature pitches under the influence of the Marangoni convection.
In my point of view, the authors study an interesting subject and worth publishing in this journal. Nevertheless, the manuscript requires moderate revision given the high standard of the journal and I would be happy to recommend this work for publication after the authors carefully addressed my comments/suggestions reported in what follows:
(1) Regarding, the effect of Marangoni Convection parameter versus the velocity filed (i.e. Figure 5), Why the two sorts of CNTs show the same behavior? The authors need to provide more details in this regard.
(2) Continuing with the first point, what the maximum value shows and the cause for the drop needs to be explained in more details. Also, why the effect of "M" vanishes at the low and higher velocity field?
(3) In Figure 12, the impact of the nanoparticle volume fraction versus pressure distribution is shown. In this case we can see some difference between the SWCNT and MWCNT. However, I do not see a satisfactory explanation for the cause of this difference. Is there a significant difference in structural or intermolecular force?
(4) How sensitive are the simulations to the physical parameter (e.g. density) considered in the model? At least, the authors need to do for one case to see if the density is a bit higher or lower, how it will affect the results.
(5) The authors need to state all the assumptions made to solve the differential equations. It is important so the reader can get how you solved them.
(6) Could this model be applied to a different shape nanofluid? it would be very interesting if the authors provide some details and if this is possible to be done.
(7) There are lots of equations and figures in the manuscript. Consider moving some of them to the supporting information.
(8) Improve the quality of Figures 2-3.
(9) The manuscript requires proofreading, there are several grammatical as well as typographical issues in the text.
(10) Consider citing few articles published in this journal, Processes.
(11) The literature review needs to be improved. The authors need to acknowledge the work of different groups (Dr. Nazemifard, Dr. Malderali, Dr. Puchard,...). Please consider the following papers: (i) Energy & Fuels, 29(9), pp.5595-5599. (ii) Physical Review E, 96(5), p.052803 (iii) Physics of Fluids 28.5 (2016): 053107; (iv) Colloids and Surfaces A: Physicochemical and Engineering Aspects, 513, pp.178-187. (v) Langmuir 33.8 (2017): 1927-1942.
Author Response
Processes-488600:
Title: “Effect of the Marangoni Convection in the Unsteady Thin Film Spray of CNTs Nanofluid”
Authors: Ali Rehman1, Taza Gul2*, Zabidin Bin Salleh2, Safyan Mukhtar3, Fawad Hussain4, Poom Kumam5,6,7
Dear Editor,
Thank you for the opportunity to revise our manuscript in accordance with the valuable
comments\ suggestions of reviewers. We incorporate with great care the constructive suggestions of all the reviewers. As a result, the manuscript is substantially improved after making the required changes.
Best Regards
Dr. Taza Gul,
Associate Professor, Department of Mathematics, City University of Science and Information Technology, Peshawar, Pakistan.
Detailed responses of queries and comments of referee’s are given below:
Academic Editor Comments
To facilitate peer review and to approximate the form of the paper to what is commonly adopted by the scientific community, authors need to introduce some changes of form in the manuscript before it can continue to peer review:
1. Figures should be placed just after the position in the text they are mentioned
Author’s Response (1)
Replaced as suggested by the honorable editor.
2. The physical situation being studied needs to be described in the beginning (section 2). So, Figure 1 needs to be described in the first paragraph of the "2. Mathematical formulation". Figures 2 and 3 seem to belong to section "3. Solution by OHAM:" and should be mentioned and described there.
Author’s Response (2)
Replaced as suggested by the honorable editor in the revised manuscript.
3. Check if all variables are defined in the text and consider adding a notation section after the conclusions.
Author’s Response (3)
Nomenclature table for the variables and parameters is added as suggested by the honorable editor in the revised manuscript.
4. The last paragraph of the introduction should describe the present paper (which it seems is what the authors intend). The use of past tense in this paragraph confuses the reader. The present tense should be used instead. For example, instead of "recent study has been focused" it should be "the present study focuses on".
Author’s Response (4)
Rectified as suggested.
Reviewer #3
Comments and Suggestions for Authors
Review of the paper titled "Effect of the Marangoni Convection in the Unsteady Thin Film Spray of CNTs Nanofluid" authored by Gul et al. (2019)
The paper focuses on the Marangoni Convection Impacts in the unsteady thin film spray of nanofluid based system (CNT). In this regard, the authors evaluate the effect of the physical parameters as a a function of velocity, pressure and temperature pitches under the influence of the Marangoni convection.
In my point of view, the authors study an interesting subject and worth publishing in this journal. Nevertheless, the manuscript requires moderate revision given the high standard of the journal and I would be happy to recommend this work for publication after the authors carefully addressed my comments/suggestions reported in what follows:
(1) Regarding, the effect of Marangoni Convection parameter versus the velocity filed (i.e. Figure 5), Why the two sorts of CNTs show the same behavior? The authors need to provide more details in this regard.
Author’s Response (1).
Rectified as suggested by the honorable reviewer and explained now in the revised manuscript.
(2) Continuing with the first point, what the maximum value shows and the cause for the drop needs to be explained in more details. Also, why the effect of "M" vanishes at the low and higher velocity field?
Author’s Response (2).
Explained now in the revised manuscript as suggested by the honorable reviewer.
(3) In Figure 12, the impact of the nanoparticle volume fraction versus pressure distribution is shown. In this case we can see some difference between the SWCNT and MWCNT. However, I do not see a satisfactory explanation for the cause of this difference. Is there a significant difference in structural or intermolecular force?
Author’s Response (3).
Explained now in the revised manuscript.
(4) How sensitive are the simulations to the physical parameter (e.g. density) considered in the model? At least, the authors need to do for one case to see if the density is a bit higher or lower, how it will affect the results.
Author’s Response (4).
The OHAM technique has been used up to the 30th order approximation and very heavy solution of the nonlinear equations obtained. Therefore, the variable effect of the density is not visible. However, it is possible in an exact solution.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The authors performed some amendments according to editor’s and reviewers’ comments. However, the manuscript needs some minor amendments before publication. The authors need to clarify the following issues while performing the further corrections:
1. Authors should be careful towards fonts’ consistency. From page 1 to page 2, fonts changed. Authors should maintain the template provided by MDPI/processes.
2. In Eq. 2, 3, 4, \partial u/ \partial t, \partial w/ \partial t, \partial T/\partial t, these transient terms are missing, respectively. Author should discuss how the ‘unsteady’ condition was incorporated in the problem.
3. In Eq. 9, what do the terms \beta and ‘b’ mean? Are they coupled with the boundary layer thickness? Authors should clarify and rewrite the equation if necessary.
4. In Table 1., the fonts are very inconsistent and also unit of temperature should of K instead of k
5. In Eq. 14, the expression of Pr is valid only for base fluid. It should be re-written for nanofluid.
6. In Fig 2,3, what are the X and Y-axis labels?
7. In Table 4, value of M is missing. Please correct.
8. In new version of Fig. 4, it is surprising that the profile did not change at all for new volume fraction of \phi=0.02 (please see the old version of Fig. 4). Same goes for Fig. 11. Author should provide justification.
9. In Fig. 8, authors should mention value of \phi.
10. Prandtl number of participating media should change with inclusion of nanoparticles. Author should justify how \phi was kept constant at different $Pr$ values in Fig. 11.
11. Author should provide the validation of code.
12. In nomenclature, C_p, \rho C_p, k_nf, \rho_f are wrongly identified. Also, authors should justify the use of B_o stated in the nomenclature.
Author Response
Processes-488600:
Title: “Effect of the Marangoni Convection in the Unsteady Thin Film Spray of CNTs Nanofluid”
Authors: Ali Rehman1, Taza Gul2*, Zabidin Bin Salleh2, Safyan Mukhtar3, Fawad Hussain4, Kottakkaran Sooppy Nisar 5 , Poom Kumam6,7,8
Dear Editor,
Thank you for the opportunity to revise our manuscript in accordance with the valuable
comments\ suggestions of reviewers. We incorporate with great care the constructive suggestions of all the reviewers. As a result, the manuscript is substantially improved after making the required changes.
Best Regards
Dr. Taza Gul,
Associate Professor, Department of Mathematics, City University of Science and Information Technology, Peshawar, Pakistan.
Reviewer 2:
Comments and Suggestions for Authors
The authors performed some amendments according to editor’s and reviewers’ comments. However, the manuscript needs some minor amendments before publication. The authors need to clarify the following issues while performing the further corrections:
1. Authors should be careful towards fonts’ consistency. From page 1 to page 2, fonts changed. Authors should maintain the template provided by MDPI/processes
Answer: Thanks, rectified now.
2. In Eq. 2, 3, 4, \partial u/ \partial t, \partial w/ \partial t, \partial T/\partial t, these transient terms are missing, respectively. Author should discuss how the ‘unsteady’ condition was incorporated in the problem.
Answer: Dear reviewer the flow is steady independent of time therefore, these terms are not mentioned in the governing equations
3. In Eq. 9, what do the terms \beta and ‘b’ mean? Are they coupled with the boundary layer thickness? Authors should clarify and rewrite the equation if necessary.
Answer: In Equation (9), is the dimensionless thickness of the liquid film and is the exterior radius of the liquid film included in the revised manuscript.
4. In Table 1., the fonts are very inconsistent and also unit of temperature should of K instead of k
Answer: Rectified
5. In Eq. 14, the expression of Pr is valid only for base fluid. It should be re-written for nanofluid.
Answer: The Prandtl number (Pr) in equation (14) is mentioned for the base fluid and presented for the base fluid in equation (12) as well and it is not for the nanofluid. The thermophysical properties of nanofluid in equation (12) are separately given in product with the (Pr). If we use (Pr) for the nanofluid then the thermophysical properties in product with (Pr) will be removed in equation (12). Moreover, the (Pr) presented in this paper is same as in the published work [36,37, 40].
6. In Fig 2,3, what are the X and Y-axis labels?
Answer: These two figures are drawn between the square residual error and order of approximations and there is no concept of axis.
7. In Table 4, value of M is missing. Please correct.
Answer: Included now
8. In new version of Fig. 4, it is surprising that the profile did not change at all for new volume fraction of \phi=0.02 (please see the old version of Fig. 4). Same goes for Fig. 11. Author should provide justification.
Answer: Rectified now
9. In Fig. 8, authors should mention value of \phi.
Answer: Rectified now
10. Prandtl number of participating media should change with inclusion of nanoparticles. Author should justify how \phi was kept constant at different $Pr$ values in Fig. 11.
Answer: The Prandtl number used in Fig.11. is related with the base fluid and have no connection with the volume fraction. The volume fraction depends on the thermophysical properties of the nanofluid given in product with the (Pr) and same as in the published work [36,37, 40].
11. Author should provide the validation of code.
Answer: The obtained results of OHAM are compared now with the Numerical (ND-Solve) method and the outcomes are displayed in Table. 6.
12. In nomenclature, C_p, \rho C_p, k_nf, \rho_f are wrongly identified. Also, authors should justify the use of B_o stated in the nomenclature.
Answer: Rectified now.
Thank you very much for the valuable points.
Author Response File: Author Response.pdf
Reviewer 3 Report
I would like to thank the authors to carefully consider my comments and points. I believe the manuscript is in a good shape for publication. As such, my recommendation is accept in its present format. However, in the accepted version please address these two minor points which can be done in a timely manner.
(i) Provide one-two sentences on the future work so the people in the field could continue and follow your methods.
(ii) Proofread your manuscript one more time
Author Response
Processes-488600:
Title: “Effect of the Marangoni Convection in the Unsteady Thin Film Spray of CNTs Nanofluid”
Authors: Ali Rehman1, Taza Gul2*, Zabidin Bin Salleh2, Safyan Mukhtar3, Fawad Hussain4, Kottakkaran Sooppy Nisar 5 , Poom Kumam6,7,8
Dear Editor,
Thank you for the opportunity to revise our manuscript in accordance with the valuable
comments\ suggestions of reviewers. We incorporate with great care the constructive suggestions of all the reviewers. As a result, the manuscript is substantially improved after making the required changes.
Best Regards
Dr. Taza Gul,
Associate Professor, Department of Mathematics, City University of Science and Information Technology, Peshawar, Pakistan.
Reviewer 3:
Comments and Suggestions for Authors
I would like to thank the author to carefully consider my comments and points. I believe the manuscript is in a good shape for publication. As such, my recommendation is accept in its present format. However, in the accepted version please address these two minor points which can be done in a timely manner.
(i) Provide one-two sentences on the future work so the people in the field could continue and follow your methods.
Answer: Included in the revised manuscript.
(ii) Proofread your manuscript one more time
Answer: manuscript checked again.
Author Response File: Author Response.pdf
