Experimental Investigation on Water Seepage through Transparent Synthetic Rough-Walled Fractures
Round 1
Reviewer 1 Report (Previous Reviewer 2)
I read this manuscript and agree that the revised paper can be accepted for publication.
Author Response
The author want to thank reviewer 1 for the careful review of the manuscript.
Reviewer 2 Report (New Reviewer)
This paper presents a study on the experimental investigation on water seepage through transparent synthetic rough- walled fractures. Fractures hydrology is always an important issue nowadays. The overall logical reasonings are exactly clear and sound. I would suggest a minor correction for this paper before it can be accepted for publication. The detailed comments listed below can be useful for the authors in improving their manuscript.
1. Abstract. Line 15-17, please to add the main problems that in this field.
2. Line 243-250, the module of 3D is so small, how to analysis the scale affection, and how about in the large scale?
3. Add the limits and disadvantages of this method.
4. Improve the English level by native speakers.
Author Response
The author want to thank reviewer 2 for the careful review of the manuscript.
Author Response File: 
Author Response.docx
Reviewer 3 Report (New Reviewer)
In this work, the authors designed an experiment to investigate the water seepage through transparent synthetic rough-walled fractures. This experimental design and results are interesting. I suggest a minor revision. Details see below,
1. What’s the novelty of this work? It is not clear in the Abstract and Introduction.
2. Please provide the materials in Part 2, Materials and methods.
3. The aperture distribution in Figure 1 is not clear. Could you provide a clear one?
4. The photos in Figure 2 are not clear. Please provide a clear on. Besides, please provide the scale bar in the photos.
5. “As shown in Figure 8, the total area of the capillary zone is reduced by about 7.5 % while the reduction in the width of the thin channels is insignificant.” Why? Could you explain more about this phenomenon?
6. Figure 7, Figure 8, and Figure 9 are not clear. Please provide clear Figures.
7. The conclusion part is too long. Could you highlight the important results? Please make it shorter.
Author Response
The author want to thank reviewer 3 for the careful review of the manuscript.
Author Response File: Author Response.docx
Reviewer 4 Report (New Reviewer)
The effects of fractal dimension and other parameters on the flow through simulated fractures is examined with laboratory experiments using 3D printed models. As well as the fractal dimension, the inclination angle, standard deviation (mean-square value of the fracture surface deviations from a flat plane) and mismatch length (the scale above which the fracture surfaces are matched). Some useful observations and insights are achieved. Overall the work is clearly presented, although the English could do with some attention (see below for some examples by line number, but there are other similar errors).
24 55 to 65 degrees (symbols)
85 is a function
90 have also
101 in natural fractures.. Their results
104 investigated using reconstructions of
132 using 3D printing
137 every minute .. training data
Section 2: too many single sentence paragraphs, try to combine sentences to form logical paragraphs.
399 flow path is created
439/440 initial conditions
444 in correspondence with [?]
468 at different times
Author Response
The author want to thank reviewer 4 for the careful review of the manuscript.
Author Response File: Author Response.docx
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
The paper by Ranjbar et al. is a study on a single plane with 3D printed fractures design, observations and a surrogate model via a tree algorithm for predicting continuous classes. The introduction is explaining briefly the development of experiments and theory on fluid flow through fractures in rocks and provide some explanation about the novelty of this work respect to the state of the art. Specifically, the authors claims that the novelty is the use of several fractures with different fractal dimensions reconstructed via 3D printing, but there are other recent examples of such an approach:
Phillips, T., Bultreys, T., Bisdom, K., Kampman, N., Van Offenwert, S., Mascini, A., ... & Busch, A. (2021). A Systematic Investigation Into the Control of Roughness on the Flow Properties of 3D‐Printed Fractures. Water Resources Research, 57(4), ewrcr-25233.
Suzuki, A., Minto, J. M., Watanabe, N., Li, K., & Horne, R. N. (2019). Contributions of 3D printed fracture networks to development of flow and transport models. Transport in Porous Media, 129(2), 485-500.
Yang, W., Zhang, D., & Lei, G. (2020). Experimental study on multiphase flow in fracture-vug medium using 3D printing technology and visualization techniques. Journal of Petroleum Science and Engineering, 193, 107394.
Suzuki, A., Bjarkason, E. K., Yamaguchi, A., Hawkins, A. J., & Hashida, T. (2022). Estimation of flow-channel structures with uncertainty quantification: Validation by 3D-printed fractures and field application. Geothermics, 105, 102480.
Yin, P., Zhao, C., Ma, J., Yan, C., & Huang, L. (2020). Experimental study of non-linear fluid flow though rough fracture based on fractal theory and 3D printing technique. International Journal of Rock Mechanics and Mining Sciences, 129, 104293.
All the abovementioned papers were neglected in the introduction, thus the novelty of this work is not clear. Moreover, the authors have used a surrogate model that is rather easy to be fitted with the observed data but do not provide particular insights on the mechanisms driving the flow dynamics in the experimental set up here used. For instance the employment of a physically based numerical model like COMSOL FEFLOW or SUTRA. Finally, there is not a clear link between the laboratory results here found and their field application. This make the manuscript more suitable for Journals dedicated to the physical processes like Water Resources Research, Geophysical Research Letters or Transport in porous media, rather than Water and in particular to the Special Issue "Groundwater Management in a Changing World: Challenges and Endeavors" to which the paper has been submitted.
Reviewer 2 Report
Reviews:
In this study, authors focuses on geometrical properties of single fractures and their influence on flow patterns. These fracture surfaces are generated by 3D printing technology. An accurate prediction algorithm was established by using Wavelet transform, and the time series of periodic flow rates over fracture outlet was estimated. Results indicated the influence of different geometric characteristics together with fracture inclination on the outlet flow rate and preferential flow paths. This work is of significance to predict flow rate and pathways in rough fractures with different geometries. I suggest Minor revision before publishing this paper.
1.The introduction dose not provide sufficient background. It is suggested to explain the background in detail and show the motivation of the research.
2.The summary of the literature is not indepth. The investigation of the previous literature should clarify how the influence of key characteristic on fracture flow path distribution has been studied and the mechanism of the influence.
3.The description of the method is not detailed enough. The explanation for important parameters such as "mismatch length" is not clear. The geometric parameters involved in Synthetic fracture designing part should be explained more clearly.
4.The figure in the paper should be clear. For the analysis of the influence of different inclination on flow rate in Figure 4, the coordinate scale corresponding to different inclination should be consistent.
5.The amount of experiment is not enough. In order to evaluate how inclination affects flow distribution, it is not enough to analyze the experimental results from three angles of 45°, 55° and 65°. There are the same problems with the analysis of fractal dimension and mismatch length.
6.The result of travel time and travel distance of the first finger to reach the outlet is different in Figure 7 and words. It should be revised carefully.
7.The derivation of the conclusion is not clear and reasonable. For the results such as the rate of change of the mean width of the first flow path, the measurement method or derivation process should be given.
8.There are few recent publications in the cited references. It is suggested that the latest research should be cited more frequently in the references.
