Study on the Fire Spread Characteristics of High-Rise Building Facades Under Strong Wind Conditions Based on the Combination of WRF and CFD
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe reviewed manuscript combines multiscale coupled simulation with model experiments to investigate the flame deflection, flame spread velocity, and temperature distribution of a high-rise building facade fire-prone wall. It uses appropriate tools and methods, including WRF, CFD, and FDS models, as well as model experiments to accurately replicate building fire scenarios under strong wind conditions.
Major comments:
1. In Section 1 (Introduction) the text should be supplemented in many places with missing references to source materials, especially when citing statistical and scientific data presented in other works or book knowledge. Similarly, Figure 1 included in this section has no reference in the text, which requires addition.
2. In line 266 in Section 2.2.3 there is a reference to Table 2-2. Probably instead of Table 2-2 it should be Table 2 or Condition 2-2 in Table 2. However, this table is only in Section 3.2. If it is mainly of methodological importance, it should be moved to Section 2.2.3, i.e. to the place of the first citation. If it mainly contains research results it can remain in Section 3.2, but in the place of the first reference it is worth adding in brackets: (Section 3.2). In Section 2.3, lines 308-309 refer to "Condition 2-1" (probably simulated working conditions or operational conditions for numerical simulation listed in Table 2). This should be better explained and referenced to the appropriate table.
3. The north and south directions in Figure 12 seem somewhat confusing, if it is shown in vertical section (as suggested by the orientation of the flame). I therefore suggest that this figure be presented in 3D, if possible. If not, then the description of this figure should be somewhat more detailed, considering the type of section and the orientation of the building to the cardinal directions.
4. The first mention of "model experiments" in Section 2 (Materials and Methods), which the Authors refer to in the Abstract, among other places, is on line 284, and the next one in Section 2.3 (Comparison and Verification of Experiments and Simulations). At the latest in Section 2.3, it should be more detailed what these "model experiments" consisted of and for what actual dimensions of the building they were conducted (because it was a small-scale experiment).
5. The data presented in Figure 15 require better commentary in terms of the reference points compared due to the different scales used on the left and right axes. Additionally, the flame spread velocity units should be specified on the vertical axes or in the caption of this figure.
6. The heading of Subsubsection 3.1.1 (line 355) apart from containing incorrect numbering, seems to be unnecessary.
7. Figures 17-23 could be supplemented with a missing legend of the temperature scale used. Alternatively, if the interpretation of the temperature range obtained is not crucial for this manuscript and these figures were made using the same temperature scale, an appropriate note can be provided in the text.
8. Figures 30-35 on the vertical axis containing the temperature should have the unit in parentheses (oC) instead of "()oC". The temperature changes near the fire-exposed wall presented in these figures require a slightly better explanation in the text. Are these temperature changes on the surface of the wall, or deep inside the insulating material, or further inside the wall?
Minor comments:
Remove unnecessary spaces or hyphens in Abstract ("high-r ise", "fa-cades"), Section 1 ("develop-ment", "sin-gle-scale", "con-sistent", "demon-strates" and "simula-tion", lines 90, 123, 134, 135 and 136, respectively).
When providing numerical data, units should be separated from the numerical value by a space (lines 88, 227-230, 238-240, 247-248, 260, 269, 286, 287-290, 299-300, 318-321, 344-350 etc.).
When referring to the names of authors of multi-author works, "et al." should always be added after the name of the first author (line 105).
The formatting of section, subsection and subsubsection titles, the formatting descriptions of figures and tables, as well as the way references are cited and the formatting of the References section, should be brought more into line with the guidelines for authors.
Figure 4 should be improved graphically (suboptimal placement of captions in frames).
In line 237, instead of "Figure 2-6" it should be "Figures 2-6".
The quality (resolution) of Figure 16 should be improved (increased).
There is a missing period at the end of the sentence in line 384.
Author Response
Dear Editors and Reviewers:
Thank you for your letter and for the editor and reviewers' comments concerning our manuscript entitled " Study on the Fire Spread Characteristics of High-rise Building Facades under Strong Wind Conditions Based on the Combination of WRF and CFD " (Applied Sciences (ISSN 2076-3417), applsci-3354737). These comments are all valuable and very helpful for revising and improving our paper. Following these comments and suggestions we have carefully revised our manuscript, and a point-to-point response letter is attached below to this email. Modifications have been made and highlighted in blue color in the main manuscript accordingly all comments have been taken as described below. Our responses text below are highlighted in blue color. The line and page numbers refer to the revised manuscript.
We have addressed all the comments and questions from you and the reviewers and thus hope that our revised MS can now find your and the reviewers’ approval.
We are looking forward to receiving your decision on our manuscript.
Yours sincerely,
Yanfeng Li
Professor
Beijing university of technology
Beijing 100124, China
E-mail: liyanfeng@bjut.edu.cn
January.19th ,2025
Response to the Reviewers’ Comment
Reviewer #1:
- The reviewer’s comment: In Section 1 (Introduction) the text should be supplemented in many places with missing references to source materials, especially when citing statistical and scientific data presented in other works or book knowledge. Similarly, Figure 1 included in this section has no reference in the text, which requires addition.
The authors’ response: We have added a reference to Figure 1 in the article
(Page 2, Lines 41-43)
- The reviewer’s comment: In line 266 in Section 2.2.3 there is a reference to Table 2-2. Probably instead of Table 2-2 it should be Table 2 or Condition 2-2 in Table 2. However, this table is only in Section 3.2. If it is mainly of methodological importance, it should be moved to Section 2.2.3, i.e. to the place of the first citation. If it mainly contains research results it can remain in Section 3.2, but in the place of the first reference it is worth adding in brackets: (Section 3.2). In Section 2.3, lines 308-309 refer to "Condition 2-1" (probably simulated working conditions or operational conditions for numerical simulation listed in Table 2). This should be better explained and referenced to the appropriate table.
The authors’ response: Table 2-2 does not appear in the text, and this part of the text has been deleted
- The reviewer’s comment:The north and south directions in Figure 12 seem somewhat confusing, if it is shown in vertical section (as suggested by the orientation of the flame). I therefore suggest that this figure be presented in 3D, if possible. If not, then the description of this figure should be somewhat more detailed, considering the type of section and the orientation of the building to the cardinal directions.
The authors’ response: We have added a detailed description of the direction of the building in the text.
(Page 9, Lines 283-286)
- The reviewer’s comment: The first mention of "model experiments" in Section 2 (Materials and Methods), which the Authors refer to in the Abstract, among other places, is on line 284, and the next one in Section 2.3 (Comparison and Verification of Experiments and Simulations). At the latest in Section 2.3, it should be more detailed what these "model experiments" consisted of and for what actual dimensions of the building they were conducted (because it was a small-scale experiment).
The authors’ response: Added a detailed introduction to the dimensions and materials of the small-sized model in the article. (Page 11, Lines312-314)
- The reviewer’s comment: The data presented in Figure 15 require better commentary in terms of the reference points compared due to the different scales used on the left and right axes. Additionally, the flame spread velocity units should be specified on the vertical axes or in the caption of this figure.
The authors’ response: Units have been added to different scales in the figure
(Page 12, Lines 335-336)
- The reviewer’s comment: Theheading of Subsubsection 3.1.1 (line 355) apart from containing incorrect numbering, seems to be unnecessary.
The authors’ response: Removed incorrect numbers
(Page 13, Lines361)
- The reviewer’s comment: Figures 17-23 could be supplemented with a missing legend of the temperature scale used. Alternatively, if the interpretation of the temperature range obtained is not crucial for this manuscript and these figures were made using the same temperature scale, an appropriate note can be provided in the text.
The authors’ response: The text label is not important for the content of this paragraph, mainly to show the deflection shape of the flame. The text has added an explanation of the flame and the corresponding color in the picture (Page 14, Lines371-372)
- The reviewer’s comment:Figures 30-35 on the vertical axis containing the temperature should have the unit in parentheses (℃) instead of "()℃". The temperature changes near the fire-exposed wall presented in these figures require a slightly better explanation in the text. Are these temperature changes on the surface of the wall, or deep inside the insulating material, or further inside the wall?
The authors’ response: The unit of the 30-35 images has been modified to (℃)
- The reviewer’s comment:Minor comments
The authors’ response: All minor comments have been modified
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsThis paper investigates the fire spread characteristics on the facades of high-rise buildings under strong wind conditions, utilizing a multi-scale simulation approach that combines WRF (Weather Research and Forecasting), Fluent (CFD), and FDS (Fire Dynamics Simulator). The primary objective is to analyze fire spread patterns in strong wind environments and provide reference data for the fire safety design of high-rise buildings. The study examines the effects of headwinds, tailwinds, and crosswinds on flame spread, presenting flame spread rates and temperature distributions for each wind direction. Below are recommendations for improving this paper. Please consider these suggestions for enhancement.
1. The paper does not explicitly mention a grid sensitivity analysis. How was the impact of grid size on simulation results validated?
2. Data extracted from WRF was used as boundary conditions for Fluent, but additional procedures to ensure data accuracy were not described.
3. The paper uses a high-resolution grid of 0.5m × 0.5m × 0.5m near the building in FDS, but the reasoning behind this choice and its impact on results is not clearly explained.
4. The differences between experimental and simulation results such as flame arrival time were not quantitatively analyzed.
5.The comparison of temperature distribution between experimental data and simulation results was not explicitly mentioned.
6.The paper does not describe the comparison of WRF simulation results with actual observational data to ensure accuracy.
7.WRF data was used as boundary conditions for Fluent, but additional procedures to verify the reliability of this data were not discussed.
8.Validation was conducted only under specific conditions (e.g., tailwinds), and validation for various wind directions and speeds was lacking.
9.Small-scale model experiments were conducted under simplified conditions, but the impact of this simplification on the results was not discussed.
10.In your manuscript, it does not describe additional validation procedures (e.g., comparison with more experimental data) to enhance the accuracy of flame spread rates.
11.The paper does not explain the reasoning behind the selection of turbulence models in Fluent and their impact on the results.
12. The interpretation of results is limited to qualitative trends, lacking quantitative data and confidence interval analysis, which are necessary to enhance the reliability of the data.
13. Furthermore, this paper lacks conclusive implications due to an excessive number of figures resulting from overly detailed explanations of the results.
Author Response
Dear Editors and Reviewers:
Thank you for your letter and for the editor and reviewers' comments concerning our manuscript entitled " Study on the Fire Spread Characteristics of High-rise Building Facades under Strong Wind Conditions Based on the Combination of WRF and CFD " (Applied Sciences (ISSN 2076-3417), applsci-3354737). These comments are all valuable and very helpful for revising and improving our paper. Following these comments and suggestions we have carefully revised our manuscript, and a point-to-point response letter is attached below to this email. Modifications have been made and highlighted in blue color in the main manuscript accordingly all comments have been taken as described below. Our responses text below are highlighted in blue color. The line and page numbers refer to the revised manuscript.
We have addressed all the comments and questions from you and the reviewers and thus hope that our revised MS can now find your and the reviewers’ approval.
We are looking forward to receiving your decision on our manuscript.
Yours sincerely,
Yanfeng Li
Professor
Beijing university of technology
Beijing 100124, China
E-mail: liyanfeng@bjut.edu.cn
January.19th ,2025
Response to the Reviewers
Reviewer #2:
- The reviewer’s comment: The paper does not explicitly mention a grid sensitivity analysis. How was the impact of grid size on simulation results validated?
The authors’ response: Added a section on grid sensitivity analysis in the revised manuscript (2.2.4 Grid sensitivity analysis) (Page 11, Lines 311-319)
- The reviewer’s comment:Data extracted from WRF was used as boundary conditions for Fluent, but additional procedures to ensure data accuracy were not described.
The authors’ response: WRF data was extracted using Python, extracting point data at heights of 2Km around the building (with one data point extracted every 1km), 10m, 50m, 100m, and 200m. The average of the two point data was then taken as the wind field data between the two points. Because the wind speed varies at every height and every cross-sectional moment, this method can only try to reproduce the actual wind speed as much as possible.
- The reviewer’s comment: The paper uses a high-resolution grid of 0.5m × 0.5m × 0.5m near the building in FDS, but the reasoning behind this choice and its impact on results is not clearly explained.
The authors’ response: Added a section on grid sensitivity analysis in revised manuscript (2.2.4 Grid sensitivity analysis) . (Page 11, Lines 311-319)
- The reviewer’s comment: The differences between experimental and simulation results such as flame arrival time were not quantitatively analyzed.
The authors’ response: Figure 16 shows the simulated spread speed and experimental spread speed, which quantitatively reflect the flame arrival time of the experiment and simulation.
(Page 12, Lines 339-347)
- The reviewer’s comment: The comparison of temperature distribution between experimental data and simulation results was not explicitly mentioned.
The authors’ response: This article mainly verifies the accuracy of the simulation results by comparing the propagation speed of experiments and simulations, without comparing the temperature
(Page 12, Lines 339-347)
- The reviewer’s comment: The paper does not describe the comparison of WRF simulation results with actual observational data to ensure accuracy.
The authors’ response: The simulated data in this article are obtained from different heights in a certain region. However, the meteorological bureau does not record detailed wind field data at different heights in each region, and they can only be simulated and restored through WRF.
- The reviewer’s comment:WRF data was used as boundary conditions for Fluent, but additional procedures to verify the reliability of this data were not discussed.
The authors’ response: This article extracted point data at a height of 2 km (with one data point extracted every 1km), 10m, 50m, 100m, and 200m around the building in WRF. Then we take the average of the two point data as the wind field data between the two points. Moreover, we use these wind field data as wind field data for Fluent software. Since the wind speed varies at each height and cross-sectional moment, this method can only reproduce the actual wind speed as much as possible.
- The reviewer’s comment:Validation was conducted only under specific conditions (e.g., tailwinds), and validation for various wind directions and speeds was lacking.
The authors’ response: Since the content of this article mainly focuses on simulation, only one representative wind direction was selected for verification.
- The reviewer’s comment:Small-scale model experiments were conducted under simplified conditions, but the impact of this simplification on the results was not discussed.
The authors’ response: This article only qualitatively verifies the simulation results through small-scale experiments under normal atmospheric conditions, because the actual wind field is constantly changing and it is difficult to achieve true reproduction. This is also a research point that can be studied on how to fully reproduce the atmospheric environment.
- The reviewer’s comment:In your manuscript, it does not describe additional validation procedures (e.g., comparison with more experimental data) to enhance the accuracy of flame spread rates.
The authors’ response: This article mainly verifies the accuracy of simulation by comparing small scale model experiments and numerical simulations of flame deflection and flame propagation speed under frontal wind conditions
- The reviewer’s comment:The paper does not explain the reasoning behind the selection of turbulence models in Fluent and their impact on the results.
The authors’ response: Added description of model selection in Fluent.
(Page 7, Lines 238-240)
- The reviewer’s comment:The interpretation of results is limited to qualitative trends, lacking quantitative data and confidence interval analysis, which are necessary to enhance the reliability of the data.
The authors’ response: This article simulates by adopting a four layered method with different wind speeds at vertical heights. The wind speed varies in different horizontal sections and vertical heights, and the wind speed and direction also change. There are too many variables to perform quantitative data fitting. Therefore, the paper can only select simulation results of a limited number of representative operating conditions for description
- The reviewer’s comment:Furthermore, this paper lacks conclusiveimplications due to an excessive number of figures resulting from overly detailed explanations of the results.
The authors’ response: Because the wind speed and direction in this study are constantly changing, it is difficult to form a conclusive summary, so a detailed explanation is needed. The strength of this study is to explore a method for simulating high-rise building fires in wind environments at meter-level resolution by coupling WRF with Fluent and FDS.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsI have reviewed the revised version of the manuscript and the response letter. It is confirmed that the authors have adequately addressed the reviewers' suggestions for improvement and provided appropriate responses. Therefore, I recommend the publication of this paper. Congratulations on your achievement, and well done!
