Study on the Interface Instability of a Shock Wave–Sub-Millimeter Liquid Droplet Interface and a Numerical Investigation of Its Breakup
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors have conducted experimental and numerical investigations on the sub-millimeter droplet deformations under the influence of a supersonic shock wave. The authors find from their experiments and VOF-based simulations that the supersonic velocities behind the show induce Kelvin-Helmholtz instabilities in the interface. This is a topic of importance in the field of atomization, and combustion. It is my opinion that this manuscript requires significant revision. There are several grammar errors. I suggest the authors seek help in fixing the grammar errors in manuscript. Here are my comments/suggestions:
Minor comments:
-Line 12: "In a supersonic gas velocity behind a shock.." This sentence is not clear, please rephrase.
-Line 32: "Involves various fields". Rewrite as "is involved in various fields".
-Line 45: "shockwave influence represent". Rewrite as "shockwave influence represents".
-Line 51: "represent". Rewrite "represents".
-There are several grammar errors of the type described above.
-Line 300: Delete “experimental”.
-Line 350: "selected the VOF". Rewrite as "selected is the VOF". Write the full-form of VOF (Volume of Fluid), cite more literature on VOF.
Major comments:
-Table 1: Please mention droplet fluid density & surface tension too. Is the droplet water? List the properties of the various gases and liquids involved.
-Figure 1: It is not clear where these experimental images are from. Are they from experiments by the authors? If so, the experimental setup and technique need to be explained clearly. Also please provide higher resolution images if possible.
-Figure 5: Please provide higher resolution images.
-Line 339: Please explain all the boundary conditions properly. What kind of outflow boundary condition have you used? Is it a non-reflective BC? Explain the "other boundary conditions".
-Figure 10: Which code/software package did you use? Please provide reference. Which package is used for the Adaptive Mesh Refinement?
-Figure 10: Provide more details on the kind of Adaptive Mesh Refinement used. Is it an oct-tree approach or a patch approach? How many levels of refinement were used here?
-Figure 13: What is the scale for reference? Show it in the picture.
-Please show results from some of the other mach numbers simulated too.
Comments on the Quality of English LanguageThere are several grammar errors. I suggest the authors seek help in fixing the grammar errors in manuscript. Here are my comments/suggestions:
Minor comments:
-Line 12: "In a supersonic gas velocity behind a shock.." This sentence is not clear, please rephrase.
-Line 32: "Involves various fields". Rewrite as "is involved in various fields".
-Line 45: "shockwave influence represent". Rewrite as "shockwave influence represents".
-Line 51: "represent". Rewrite "represents".
-There are several grammar errors of the type described above.
-Line 300: Delete “experimental”.
-Line 350: "selected the VOF". Rewrite as "selected is the VOF". Write the full-form of VOF (Volume of Fluid), cite more literature on VOF.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe paper is interesting, but I would like to see some improvements before accepting it.
I am not sure the method is VOF. It is actually a two-fluid approach. Much more details about the numerical method should be added. For example, how is the droplet surface tracked? Please also add the values for the constants, such as water density and others.
Is the mixture assumed to be in an isothermal state? This should be mentioned. If not, the energy eqn should be added.
Also, is a commercial software being used? Or is it a in-house numerical code? This should be added, specially if it is a commercial code.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
