Assessment of Cavitation Models for Compressible Flows Inside a Nozzle

Round 1

Reviewer 1 Report

The work evaluates cavitating flows where compressibility plays an important role.

Other than the following very minor remarks, the introduction is well structured and written:

Lines 35-36 : should this read ...impairs the performance, rather than their performance?

Line 44: I believe the sentence begining Prediction of ... should read "The prediction", or perhaps some other word.

Section 2:

It may be better to write "Reproduced with permission" in the caption of Figure 1.

Line 111 and 114: It may be better to replace "They" with the appropriate reference

There may be something wrong in 125.

Section 4:

Although I appreciate that several grids were used, there is not sufficient information on the performance of the final grid: What is the uncertainty (using any method the authors prefer), what was the refinement ratio?

Please show a figure of the mesh.

All scales in figure 6 and 10 should be the same to enable a visual conparison.

What is missing from the study is a discussion on the influence of turbulence modelling. The k-epsilon model is not usually preferred, and although the authors compared some parameters with experimental data, it would benefit the study to incorporate a discussion on what the turbulence dependence of the problem is.

Author Response

Please see attached.

Author Response File: Author Response.pdf

Reviewer 2 Report

In this paper, two cavitation models for compressible cavitating flows within a single hole nozzle are assessed. The research point is novelty and interesting. The manuscript is well-organized and readability. This manuscript can be acceptable. To improve the quality of the paper, some recommendations may be useful for the authors.

1. The introduction could be extended to better show the current status of the Research. The contributions of this paper must be expressed in detail in Introduction.
2. The choice of turbulence model must be compared by data. Why must use this model? What’s the advantage?
3. More details of experiment could be added.
4. Some long sentences could be replaced by short and simple sentences.

Author Response

Please see attached.

Author Response File: Author Response.pdf

Reviewer 3 Report

Paper ID: fluids-875067

Title: Assessment of cavitation models for compressible flows inside a nozzle

Authors: Aishvarya Kumar, Ali Ghobadian and Jamshid M. Nouri

General Remarks

The paper describes the comparative use of two cavitation models for compressible cavitating confined flow within a single-hole nozzle. The models proposed for the evaluation were Schnerr and Sauer and Zwart-Gerber-Belamri. The liquid compressibility is modeled by using the Tait equation, whereas the vapor compressibility is modeled by using the ideal gas law. The subject of the research is actual, therefore the arousing scientific interest of the submitted paper may sustain the publication in the journal. However, there are some necessary improvements that have to be done prior to the paper final acceptance.

Arguments:

1. Major problems for which the authors are expected to give consistent explanations:
1. It is widely known that cavitation is a three-dimensional unsteady phenomenon that develops randomly in space and time. Under such circumstances, the reported approach is only a two-dimensional one and the numerical simulation was a steady-state one. Authors are strongly invited to motivate their choice and to emphasize the price the reported results must pay for the accepted simplifications;
2. Same remark regarding the dimensionality of the problem regards the turbulence treatment;
3. Although still in use, the realizable k-epsilon model used in the study looks well out of fashion nowadays. This is especially true when the chosen model proposed in 1994 (Ref. 29) is already more than a quarter of century old. Do the authors performed a comparative studies with other newer models, such as, for instance, k-omega SST, or with hybrid models such as DES and DDES, which proved their superiority in most of the reported cases? (for conformity, see: https://www.mdpi.com/2077-1312/8/4/297/htm, https://www.mdpi.com/2077-1312/6/2/56/htm,  https://www.mdpi.com/2077-1312/7/11/404/htm, https://www.sciencedirect.com/science/article/abs/pii/S0029801812004489?via%3Dihub). Because the above models are contained in the newer released versions of the ANSYS Fluent package, based on comparisons with the researches listed above (and others, off course!) the authors are strongly invited to provide consistent and well-founded reasons for choosing the realizable k-epsilon turbulence model against the abovementioned references;
4. The section 6 “Conclusions” seems to be rather poor in usable information for the reader. I suggest the authors to revise it and provide more systemized proved findings.

1. Secondary problems:
1. The resolution of Figure 3 is very poor. I suggest the authors to redraw it according to the instructions of the editor;
2. The use of yellow colon in Figure 4 is inappropriate since it cannot be distinguished properly. I suggest the authors to use a more contrasting color or to use a another symbol for representing the Grid 6 solution;
3. Similarly, for Figure 14;
4.  The Reference section suffers and need to be revised. In the followings only some examples are given:

1. The authors are invited to revise the way the citation of the last author is done, i.e. with or without “and” before. This is necessary since both rules are used in the paper Reference section;
2. All the citations must end with a full stop;

• Ref. 3 does not respect the editor rule for referencing. I believe that instead of “Henry, R.E.; Grolmes, M.A.; Fauske, H.K. PRESSURE-PULSE PROPAGATION IN TWO-PHASE ONE-AND 579 TWO-COMPONENT MIXTURES.; 1971”; the authors better use the following citation: “Henry, R. E.; Grolmes, M. A.; Fauske, H. K., “Pressure-pulse propagation in two-phase one-and two-component mixtures”, Technical Report No. ANL-7792, Argonne National Lab., Ill, doi:10.2172/4043485, 1971;

1. Ref. 6 does not have any information regarding its status. If it is a book, the editor name is missing. If not, all the other missing data are required.
2. Same for Refs. 7, 9, 11, 19, 27, 30;
3. Ref. 27 “Manninen, M.; Taivassalo, V.; Kallio, S.; others On the mixture model for multiphase flow. 1996.” cannot be found it the literature based on the information provided in the reference list. Probably the authors meant “Manninen, M.; Taivassalo, V.; Kallio, S.; Akademi, A. 1996, VTT publications 288, ESPOO, Finland”.

• Ref. 30 “Kumar, A. Investigation of in-nozzle flow characteristics of fuel injectors of IC engines; 2017” cannot be found it the literature based on the information provided in the reference list;
• Ref. 33 “Yuan, W.; Sauer, J.; Schnerr, G.H. Modeling and computation of unsteady cavitation flows in injection 636 nozzles. M{é}canique Ind. 2001, 2, 383–394” contains forbidden characters “M{é}canique”;

1. Ref. 40 is obviously misleading the reader. According to the rules of editor, instead of “Unsteady cavitating flow: a new cavitation model based on a modified front capturing method and bubble dynamics. In Proceedings of the Proceedings of 2000 ASME fluid engineering summer conference; 2000; pp. 11–15” the reference should probably look as: Sauer, J., Schnerr, G. H. Unsteady Cavitating Flow: A New Cavitation Model Based on Modified Front Capturing Method and Bubble Dynamics. In Proceedings of the 2000 ASME Fluids Engineering Division summer meeting, Boston, MA, 1073-1080;
2. The rule of capitalizing the first letter of the sentence is not respected in the Reference list. Examples:
   1. Karplus, H.B. Velocity of Sound in a Liquid Containing Gas Bubbles. J. Acoust. Soc. Am. 1957, 29, 1261–575 1262.
   2. Waldrop, M.; Thomas, F. Video: Shock Wave Propagation: Cavitation of Dodecane in a Converging-594 Diverging Nozzle 2015.
   3. Battistoni, M.; Som, S.; Longman, D.E. Comparison of Mixture and Multifluid Models for In-Nozzle Cavitation Prediction. J. Eng. Gas Turbines Power 2014, 136, 61506.
   4. Battistoni, M.; Grimaldi, C.N. Analysis of Transient Cavitating Flows in Diesel Injectors Using Diesel and Biodiesel Fuels. SAE Int. J. Fuels Lubr. 2010, 3, 2010-01–2245, doi:10.4271/2010-01-2245.

1. I do suggest the authors to carefully check all the other citations;
2. A thorough additional proofreading is dully necessary since there are English language problems, e.g. L634 “Fluent, A. 14.5. Theory Guid. 2012, 117” instead of the correct “ANSYS… Theory Guide”.

Author Response

Please see attached.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Dear Authors,

Thank you for your responces to the comments. I find that the paper is suitable for publication.

Reviewer 2 Report

The results are interesting and this paper is well organized. This manuscript can be acceptable.