An experimental study on the heat transport in porous media convection
Pith reviewed 2026-06-27 23:25 UTC · model grok-4.3
The pith
Porous media convection transitions through five regimes as the Rayleigh-Darcy number rises, shifting from Darcy-like to classical Rayleigh-Bénard behavior.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The present system undergoes a transition through five distinct regimes: I. Conduction, II. Convection, III. Oscillation, IV. Transition, V. Classical Rayleigh–Bénard convection. This transitional process bridges the gap between Rayleigh–Darcy-like behaviour and Rayleigh–Bénard-like behaviour in porous media convection. By varying the permeability of the matrix, the Darcy number is shown to have a profound impact on the transitional processes across different regimes. Flow field measurements reveal that the flow structures within Regime IV and Regime V evolve from several horizontally stacked convection rolls to a single-roll structure, and the pore-scale Reynolds number exceeds unity in the
What carries the argument
Porous-medium Nusselt number Nu_m and local temperature statistics used to delineate the five regimes while the 3D-printed lattices allow controlled variation of Darcy number.
If this is right
- The Darcy number controls the Rayleigh-Darcy number values at which each regime boundary occurs.
- In the transition and classical regimes the large-scale flow changes from multiple stacked rolls to a single roll.
- Pore-scale Reynolds number exceeds one precisely when the system leaves the oscillation regime.
- The phase diagram in Ra-Da space locates all five regimes for the range of permeabilities tested.
Where Pith is reading between the lines
- The reported sequence supplies a concrete map that could be used to predict regime boundaries in geothermal or subsurface flow models once permeability is known.
- If the oscillation regime is tied to a specific instability, its boundaries might be predictable from linear stability analysis of the lattice geometry.
- Extending the measurements to higher Rayleigh-Darcy numbers could reveal whether additional regimes appear beyond classical Rayleigh-Bénard convection.
Load-bearing premise
The 3D-printed lattice structures produce flow and heat transport statistics representative of natural porous media without introducing dominant artifacts from the printing process or lattice geometry.
What would settle it
Repeating the experiment with a natural sand or bead pack instead of the 3D-printed lattice and finding a different number of regimes or no clear bridging between Darcy-like and Rayleigh-Bénard-like behavior would falsify the reported sequence.
Figures
read the original abstract
We investigate the heat transport in porous media convection over a wide Rayleigh--Darcy number range of $26.8\leq Ra\leq 2.62\times 10^5$, and a Darcy number range of $6.18\times10^{-7}\leq Da\leq 1.21\times 10^{-5}$. In the experiments, we employ 3D-printed lattice structures as the solid porous matrix and water as the working fluid. Quantitative analyses of the porous medium Nusselt number $Nu_m$ and local temperature statistics reveal that the present system undergoes a transition through five distinct regimes: I. Conduction, II. Convection, III. Oscillation, IV. Transition, V. Classical Rayleigh--B\'enard convection. This transitional process bridges the gap between Rayleigh--Darcy-like behaviour and Rayleigh--B\'enard-like behaviour in porous media convection. By varying the permeability of the matrix, we further examine the role of the Darcy number $Da$, which turns out to have a profound impact on the transitional processes across different regimes. Flow field measurements reveal that the flow structures within Regime IV and Regime V evolve from several horizontally stacked convection rolls to a single-roll structure, and the pore-scale Reynolds number both exceeds unity in these two regimes. Finally, we report the corresponding phase diagram in the $Ra$-$Da$ space.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript reports experiments on heat transport in porous media convection using 3D-printed lattice structures with water as the fluid. Over 26.8 ≤ Ra ≤ 2.62×10^5 and 6.18×10^{-7} ≤ Da ≤ 1.21×10^{-5}, quantitative Nu_m(Ra,Da) and temperature statistics identify five regimes (I: conduction, II: convection, III: oscillation, IV: transition, V: classical Rayleigh-Bénard convection). Da strongly affects the transitions; flow visualizations show stacked rolls evolving to a single-roll structure with pore-scale Re > 1 in regimes IV and V. A phase diagram in Ra-Da space is presented.
Significance. If the regime boundaries and lattice representativeness hold, the work supplies a useful experimental bridge between Rayleigh-Darcy and Rayleigh-Bénard limits in porous media, including the quantified role of permeability, flow structure evolution, and a phase diagram. The controlled variation of Da via 3D-printed matrices and the inclusion of permeability calibration and visualizations are strengths.
minor comments (3)
- [Abstract] Abstract: The regime list is given without any numerical boundaries in Ra or Da; the full text supplies these but the abstract would benefit from at least one example boundary value per transition for immediate context.
- [Introduction/Notation] Notation: The symbol Ra is used for the Rayleigh-Darcy number throughout; an explicit definition (including the permeability scaling) in the introduction or methods would prevent confusion with the standard Rayleigh number.
- [Results/Figures] Figure clarity: Ensure all regime-transition figures include error bars on Nu_m and temperature statistics, and label the specific Ra-Da values at which regime boundaries occur.
Simulated Author's Rebuttal
We thank the referee for their positive assessment of our manuscript, including recognition of the controlled variation of Da, permeability calibration, flow visualizations, and the phase diagram in Ra-Da space. The referee's summary accurately reflects our experimental findings on the five regimes bridging Rayleigh-Darcy and Rayleigh-Bénard behaviors. No major comments were provided in the report.
Circularity Check
No significant circularity
full rationale
This paper is a purely experimental report on heat transport in 3D-printed porous media. It identifies five regimes via direct measurements of Nu_m(Ra,Da) and temperature statistics without any derivations, fitted models, predictions, or load-bearing self-citations. Regime boundaries and flow visualizations are presented as empirical observations, with no equations or ansatzes that reduce to inputs by construction. The central claims rest on experimental data reduction rather than any self-referential chain.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Rayleigh-Darcy and Darcy numbers are the controlling dimensionless parameters for the observed transitions.
Reference graph
Works this paper leans on
-
[1]
The training process of many deep networks explores the same low-dimensional manifold
Noto, Daisuke and Letelier, Juvenal A. and Ulloaet, Hugo N. , title =. Proceedings of the National Academy of Sciences , ISSN =. doi:10.1073/pnas , year =
-
[2]
Liang, Yu and Wen, Baole and Hesse, Marc A. and DiCarlo, David , title =. Geophys. Res. Lett. , volume =. doi:10.1029/2018gl079849 , year =
-
[3]
Huang, S. D. and Kaczorowski, M. and Ni, R. and Xia, K. Q. , title =. Phys. Rev. Lett. , volume =. 2013 , type =. doi:10.1103/PhysRevLett.111.104501 , url =
-
[4]
Xia, Ke-Qing and Huang, Shi-Di and Xie, Yi-Chao and Zhang, Lu , title =. Nat. Sci. Rev. , pages =. 2023 , type =. doi:10.1093/nsr/nwad012 , url =
-
[5]
De Paoli, Marco and Yerragolam, Guru Sreevanshu and Lohse, Detlef and Verzicco, Roberto , title =. Comput. Phys. Commun. , volume =. doi:10.1016/j.cpc.2025.109579 , year =
-
[6]
Joseph, D. D. and Nield, D. A. and Papanicolaou, G. , title =. Water Resour. Res. , volume =. doi:https://doi.org/10.1029/WR018i004p01049 , url =
-
[7]
Combarnous, M.A. and Bories, S.A. , title =. Adv. Hydrosci. , volume =. doi:10.1016/B978-0-12-021810-3.50008-4 , year =
-
[8]
Current trends and future directions in turbulent thermal convection , journal =. 2013 , issn =. doi:https://doi.org/10.1063/2.1305201 , url =
-
[9]
and Ennis-King, Jonathan , title =
Emami-Meybodi, Hamid and Hassanzadeh, Hassan and Green, Christopher P. and Ennis-King, Jonathan , title =. Int. J. Greenh. Gas Control , volume =. doi:10.1016/j.ijggc.2015.04.003 , year =
-
[10]
Nield, Donald A. and Bejan, Adrian , title =. doi:10.1007/978-3-319-49562-0 , year =
-
[11]
Zanganeh, G. and Pedretti, A. and Zavattoni, S. and Barbato, M. and Steinfeld, A. , title =. Sol. Energy , volume =. doi:10.1016/j.solener.2012.07.019 , year =
-
[12]
De Paoli, M. , title =. Eur. Phys. J. E , volume =. doi:10.1140/epje/s10189-023-00390-8 , year =
-
[13]
Malkus, W. V. R. , title =. Proc. R. Soc. Lond. A , volume =. doi:10.1098/rspa.1954.0197 , year =
-
[14]
Howard, L. N. , title =. Applied Mechanics , editor =. 1966 , publisher =
1966
-
[15]
and Constantin, Peter , title =
Doering, Charles R. and Constantin, Peter , title =. J. Fluid Mech. , volume =. doi:10.1017/S002211209800281X , year =
-
[16]
and Johnston, Hans and Worthing, Rodney A
Otero, Jesse and Dontcheva, Lubomira A. and Johnston, Hans and Worthing, Rodney A. and Kurganov, Alexander and Petrova, Guergana and Doering, Charles R. , title =. J. Fluid Mech. , volume =. doi:10.1017/S0022112003007298 , year =
-
[17]
Ahlers, Guenter and Grossmann, Siegfried and Lohse, Detlef , title =. Rev. Mod. Phys. , volume =. doi:10.1103/RevModPhys.81.503 , year =
-
[18]
Lohse, D. and Xia, K. Q. , title =. Annu. Rev. Fluid Mech. , volume =. doi:10.1146/annurev.fluid.010908.165152 , year =
-
[19]
Xia, Ke-Qing and Chong, Kai Leong and Ding, Guang-Yu and Zhang, Lu , title =. Acta Mech. Sin. , volume =. doi:10.1007/s10409-024-24287-x , year =
-
[20]
Huppert, Herbert E. and Neufeld, Jerome A. , title =. Annu. Rev. Fluid Mech. , volume =. doi:10.1146/annurev-fluid-011212-140627 , year =
-
[21]
Hewitt, D. R. and Neufeld, J. A. and Lister, J. R. , title =. Phys. Rev. Lett. , volume =. doi:10.1103/PhysRevLett.108.224503 , year =
-
[22]
Pirozzoli, Sergio and De Paoli, Marco and Zonta, Francesco and Soldati, Alfredo , title =. J. Fluid Mech. , volume =. doi:10.1017/jfm.2020.1178 , year =
-
[23]
Liu, Shuang and Jiang, Linfeng and Chong, Kai Leong and Zhu, Xiaojue and Wan, Zhen-Hua and Verzicco, Roberto and Stevens, Richard J. A. M. and Lohse, Detlef and Sun, Chao , title =. J. Fluid Mech. , volume =. doi:10.1017/jfm.2020.309 , year =
-
[24]
and Avila, Marc and Jin, Yan , title =
Gasow, Stefan and Lin, Zhe and Zhang, Hao Chun and Kuznetsov, Andrey V. and Avila, Marc and Jin, Yan , title =. J. Fluid Mech. , volume =. doi:10.1017/jfm.2020.164 , year =
-
[25]
Korba, David and Li, Like , title =. J. Fluid Mech. , volume =. doi:10.1017/jfm.2022.491 , year =
-
[26]
Xu, Ao and Xu, Ben-Rui and Xi, Heng-Dong , title =. Phys. Rev. Fluids , volume =. doi:10.1103/PhysRevFluids.8.093504 , year =
-
[27]
Li, Junyi and Yang, Yantao and Sun, Chao , title =. J. Fluid Mech. , volume =. doi:10.1017/jfm.2025.213 , year =
-
[28]
Graham, M. D. and Steen, P. H. , title =. J. Fluid Mech. , volume =. doi:10.1017/S0022112094004386 , year =
-
[29]
De Paoli, Marco and Zonta, Francesco and Soldati, Alfredo , title =. Phys. Fluids , volume =. doi:10.1063/1.4947425 , year =
-
[30]
Lister, C. R. B. , title =. J. Fluid Mech. , volume =. doi:10.1017/S0022112090000143 , year =
-
[31]
Kladias, N. and Prasad, V. , title =. J. Thermophys. Heat Transf. , volume =. doi:10.2514/3.301 , year =
-
[32]
Keene, Daniel J. and Goldstein, R. J. , title =. J. Heat Transfer , volume =. doi:10.1115/1.4029087 , year =
-
[33]
Ataei-Dadavi, Iman and Chakkingal, Manu and Kenjeres, Sasa and Kleijn, Chris R. and Tummers, Mark J. , title =. Int. J. Heat Mass Transf. , volume =. doi:10.1016/j.ijheatmasstransfer.2018.10.118 , year =
-
[34]
, title =
Schneider, K.-J. , title =. Progress in Refrigeration Science and Technology , publisher =. 1965 , doi =
1965
-
[35]
Zhang, Lu and Xia, Ke-Qing , title =. J. Fluid Mech. , volume =. doi:10.1017/jfm.2023.600 , year =
-
[36]
Hewitt, Duncan R and Neufeld, Jerome A and Lister, John R , title =. J. Fluid Mech. , volume =. doi:10.1017/jfm.2014.216 , year =
-
[37]
Zhang, Lu and Xia, Ke-Qing , title =. Phys. Rev. Fluids , volume =. doi:10.1103/PhysRevFluids.8.023501 , year =
-
[38]
Horton, C. W. and Rogers, F. T., Jr. , title =. J. Appl. Phys. , volume =. doi:10.1063/1.1707601 , year =
-
[39]
Lapwood, E. R. , title =. Math. Proc. Camb. Philos. Soc. , volume =. doi:10.1017/S030500410002452X , year =
-
[40]
Xi, H. D. and Xia, K. Q. , title =. Phys. Fluids , volume =. doi:10.1063/1.2920444 , year =
-
[41]
Huang, S. D. and Xia, K. Q. , title =. J. Fluid Mech. , volume =. doi:10.1017/jfm.2016.181 , year =
-
[42]
Chen, Xin and Huang, Shi-Di and Xia, Ke-Qing and Xi, Heng-Dong , title =. J. Fluid Mech. , volume =. doi:10.1017/jfm.2019.624 , year =
-
[43]
Zhang, Lu and Dong, Jing and Xia, Ke-Qing , title =. J. Fluid Mech. , volume =. doi:10.1017/jfm.2022.187 , year =
-
[44]
Sugiyama, K. and Ni, R. and Stevens, R. J. A. M. and Chan, T. S. and Zhou, S. Q. and Xi, H. D. and Sun, C. and Grossmann, S. and Xia, K. Q. and Lohse, D. , title =. Phys. Rev. Lett. , volume =. doi:10.1103/PhysRevLett.105.034503 , year =
-
[45]
Ni, R. and Huang, S. D. and Xia, K. Q. , title =. J. Fluid Mech. , volume =. doi:10.1017/jfm.2015.433 , year =
-
[46]
Xi, H. D. and Xia, K. Q. , title =. Phys. Rev. E , volume =. doi:10.1103/PhysRevE.75.066307 , year =
-
[47]
Hartline, Beverly K. and Lister, C. R. B. , title =. J. Fluid Mech. , volume =. doi:10.1017/S0022112077000202 , year =
-
[48]
Elder, J. W. , title =. J. Fluid Mech. , volume =. doi:10.1017/S0022112067000023 , year =
-
[49]
and LeFur, B
Combarnous, M. and LeFur, B. , title =. C. R. Acad. Sci. Paris B , volume =
-
[50]
Yen, Yin-Chao , title =. Int. J. Heat Mass Transf. , volume =. doi:10.1016/0017-9310(74)90136-7 , year =
-
[51]
Buretta, R. J. and Berman, A. S. , title =. J. Appl. Mech. , volume =. doi:10.1115/1.3423818 , year =
-
[52]
Caltagirone, J. P. and Meyer, G. and Mojtabi, A. , title =. J. Mécanique , volume =
-
[53]
Holst, P. H. and Aziz, K. , title =. Int. J. Heat Mass Transf. , volume =. doi:10.1016/0017-9310(72)90167-6 , year =
-
[54]
Caltagirone, J. P. and Fabrie, P. , title =. Eur. J. Mech. B Fluids , volume =
-
[55]
Caltagirone, J. P. and Cloupeau, M. and Combarnous, M. , title =. C. R. Acad. Sci. Paris B , volume =
-
[56]
Walker, K. and Homsy, G. M. , title =. J. Heat Transfer , volume =. doi:10.1115/1.3450692 , year =
-
[57]
Ren, Lei and Tao, Xin and Zhang, Lu and Ni, Ming-Jiu and Xia, Ke-Qing and Xie, Yi-Chao , title =. J. Fluid Mech. , volume =. doi:10.1017/jfm.2022.866 , year =
-
[58]
Niemela, J. J. and Skrbek, L. and Sreenivasan, K. R. and Donnelly, R. J. , title =. Nature , volume =. 2000 , type =. doi:10.1038/35009036 , url =
-
[59]
Sano, M. and Wu, X. Z. and Libchaber, A. , title =. Phys. Rev. A Gen. Phys. , volume =. 1989 , type =. doi:10.1103/physreva.40.6421 , url =
-
[60]
Zhou, S. Q. and Xia, K. Q. , title =. Phys. Rev. Lett. , volume =. 2001 , type =. doi:10.1103/PhysRevLett.87.064501 , url =
-
[61]
Wang, Q. and Verzicco, R. and Lohse, D. and Shishkina, O. , title =. Phys. Rev. Lett. , volume =. 2020 , type =. doi:10.1103/PhysRevLett.125.074501 , url =
-
[62]
van der Poel, Erwin P. and Stevens, Richard J. A. M. and Sugiyama, Kazuyasu and Lohse, Detlef , title =. Phys. Fluids , volume =. doi:10.1063/1.4744988 , year =
-
[63]
De Paoli, Marco and Pirozzoli, Sergio and Zonta, Francesco and Soldati, Alfredo , title =. J. Fluid Mech. , volume =. doi:10.1017/jfm.2022.461 , year =
-
[64]
Zhu, Xiaojue and Fu, Yifeng and De Paoli, Marco , title =. J. Fluid Mech. , volume =. doi:10.1017/jfm.2024.528 , year =
-
[65]
Wen, Baole and Corson, Lindsey T. and Chini, Gregory P. , title =. J. Fluid Mech. , volume =. doi:10.1017/jfm.2015.205 , year =
-
[66]
Xia, K. Q. and Sun, C. and Zhou, S. Q. , title =. Phys. Rev. E , volume =. 2003 , type =. doi:10.1103/PhysRevE.68.066303 , url =
-
[67]
Xi, H. D. and Xia, K. Q. , title =. Physical Review E , volume =. 2008 , type =. doi:10.1103/PhysRevE.78.036326 , url =
-
[68]
Stringano, G. and Verzicco, R. , title =. J. Fluid Mech. , volume =. doi:10.1017/s0022112005007378 , year =
-
[69]
Weiss, Stephan and Ahlers, Guenter , title =. J. Fluid Mech. , volume =. doi:10.1017/s0022112010005963 , year =
-
[70]
Elder, J. W. , title =. J. Fluid Mech. , volume =. doi:10.1017/s0022112065001258 , year =
-
[71]
Xu, Fang and Zhang, Lu and Xia, Ke-Qing , title =. J. Fluid Mech. , volume =. doi:10.1017/jfm.2024.164 , year =
-
[72]
Alam, Parvez and Madanan, Umesh , title =. Int. J. Therm. Sci. , volume =. doi:10.1016/j.ijthermalsci.2025.110409 , year =
-
[73]
Bavandla, K. C. and Srinivasan, V. , title =. J. Heat Transfer , volume =. doi:10.1115/1.4064327 , year =
-
[74]
Bavandla, K. C. and Srinivasan, V. , title =. J. Heat Transfer , volume =. doi:10.1115/1.4067338 , year =
-
[75]
Schwendener, Dario and Noir, Jerome and Latt, Jonas and Coreixas, Christophe and Kong, Xiang-Zhao , title =. J. Fluid Mech. , volume =. doi:10.1017/jfm.2025.11014 , year =
-
[76]
Karani, H. and Huber, C. , title =. Phys. Rev. E , volume =. 2017 , type =. doi:10.1103/PhysRevE.95.033123 , url =
-
[77]
Wang, M. Y. and Bejan, A. , title =. Int. Commun. Heat Mass Transf. , volume =. 1987 , type =. doi:10.1016/0735-1933(87)90041-8 , url =
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