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REVIEW 4 major objections 6 minor 38 references

Hierarchical Dimensionless Learning (Hi-{\pi}): A physics-data hybrid-driven approach for discovering dimensionless parameter combinations

T0 review · 4 major / 6 minor · reviewed 2026-08-15 · deepseek-v4-flash

Pith's one-line read A three-stage pipeline that combines Buckingham-Pi dimensional analysis, multi-branch symbolic regression, and polynomial regression can rediscover a system's intrinsic dimensionless parameter combinations from data, the paper argues.

desk verdict A sensible incremental method for extracting multiple dimensionless groups via multi-branch symbolic regression, but the paper's central claim of basis-independence is asserted without proof and needs demonstration before the 'intrinsic parameters' narrative holds. read the letter →

arxiv 2507.18332 v1 pith:PCZGSQ2A submitted 2025-07-24 physics.flu-dyn cs.LGphysics.data-an

classification physics.flu-dyncs.LGphysics.data-an
keywords symbolicregressionparameterreductiondimensionalanalysisdata-drivendiscoverydimensionlessnumbersBuckinghamPitheoremRayleigh–Bénardconvectionpipeflow
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

Hi-π is a three-stage pipeline: dimensional analysis first compresses the raw physical inputs into an arbitrary set of dimensionless groups, symbolic regression then proposes several dimensionless parameter combinations using a multi-branch tree, and polynomial regression scores each combination by predictive accuracy. The paper claims that this pipeline can rediscover the physically meaningful dimensionless numbers of a system without the user knowing them in advance, including multiple groups at once. Across the tested cases, it recovers the Rayleigh and Prandtl numbers for Rayleigh–Bénard convection, the Reynolds number and relative roughness for circular-pipe flow, and a form of the compressibility correction for subsonic flow. A sympathetic reader would care because this offers a data-driven route to the key insight of dimensional analysis: finding the few combinations of variables that actually organize a physical problem.

What carries the argument

The carrying object is a composition of three maps: a Buckingham-Pi dimensional embedding that sends the physical inputs $\boldsymbol{p}$ to an arbitrary set of dimensionless variables $\boldsymbol{s}$; a multi-branch symbolic-regression tree that searches for $n$ parameter combinations $\pi_i = g_i(\boldsymbol{s})$ without restricting them to power-law products; and a multivariate polynomial regression $F(\boldsymbol{\pi}, \boldsymbol{\beta})$ whose squared error is the loss that drives the symbolic search. The multi-branch tree structure is what allows several parameter combinations to be extracted simultaneously, and the polynomial order serves as an explicit complexity knob: the paper selects the 'best' parameter combination by looking for the order at which the loss stops improving, balancing accuracy against interpretability.

What would settle it

Run the circular-pipe example with a different valid basis, for instance $w_{b1}' = (1,-1,1,0)^T$ and $w_{b2}' = (0,0,-1,1)^T$, which yield $\mathrm{Re} = VD/\nu$ and $\varepsilon/D$, and apply the Hi-π pipeline to the same experimental pipe-flow data. If the extracted optimal combination at the selected polynomial order is no longer $\mathrm{Re}$ and $\varepsilon/D$, or if the order-loss trade-off curve changes shape, then the claimed intrinsic extraction fails.

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Extended reading notes

Core claim

The central claim is that a hierarchy of dimensional reduction, unconstrained symbolic search, and polynomial mapping can extract the intrinsic dimensionless parameter combinations of a physical system from data, even when several such combinations matter simultaneously. In the cases presented, the extracted combinations coincide with the standard ones: the Rayleigh number and Prandtl number for Rayleigh–Bénard convection, the Reynolds number and relative roughness for rough circular-pipe flow, and the incompressible pressure coefficient together with the Prandtl–Glauert factor for the Karman–Tsien compressibility correction. The paper further claims that this extraction is robust to the data range and to differences in sensitivity between parameter combinations, whereas single-combination extraction methods are not.

Load-bearing premise

The final extracted dimensionless parameter combinations are independent of which valid set of dimensionless basis vectors is chosen at the Buckingham-Pi step; the paper asserts this for the pipe-flow example but supplies no proof or systematic demonstration.

Editorial extensions

If this is right

  • A user can start from any valid set of dimensionless groups produced by Buckingham-Pi analysis and still recover the conventional physical groups, if the claimed independence from the initial basis holds.
  • Multi-branch symbolic regression can find physically essential but weak dimensionless numbers alongside a dominant one, which is a case where single-combination methods fail.
  • Feeding the discovered parameter combinations into symbolic regression as transformed variables materially increases the success rate of discovering complex hierarchical formulas such as the Karman–Tsien correction.
  • The iterative strategy of increasing the number of branches until prediction error stops improving gives a data-driven estimate of the intrinsic dimension of a system's low-dimensional manifold.
  • Comparing the polynomial-order-versus-loss curve across candidate parameter combinations provides a complexity-aware criterion for selecting the most physically interpretable dimensionless representation.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • If the basis-independence claim holds generally, Hi-π can be understood not just as a rediscovery tool but as a data-driven way to select a canonical coordinate system on the space of dimensionless groups, which would connect it to parameter-identifiability and active-subspace ideas.
  • A natural test beyond the paper's four examples would be a system whose true dimensionless group is not already known from classical theory; success there, rather than in rediscovering known groups, would be the stronger evidence that the method finds intrinsic structure.
  • Because the paper notes that polynomial mappings may be limited in high-dimensional complex problems, replacing the polynomial scoring layer with a model-free measure such as mutual information is a plausible extension that could broaden the method's range.
  • The claim that extracted groups are 'intrinsic' depends on the output quantity chosen: rerunning the pipeline with a different target quantity would likely produce different optimal parameter combinations, so the method discovers groups that characterize a specific input-output relationship rather than the system in isolation.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

4 major / 6 minor

Summary. The paper proposes Hi-π, a physics-data hybrid method that combines Buckingham-Pi dimensional analysis, multi-branch symbolic regression (PySR), and polynomial regression to extract dimensionless parameter combinations from data. The method is demonstrated on three synthetic mathematical examples and on three fluid-mechanics problems: Rayleigh-Bénard convection (where it claims to rediscover the Rayleigh and Prandtl numbers), rough circular pipe flow (where it claims to rediscover the Reynolds number and relative roughness), and subsonic compressibility correction (where it recovers the Prandtl-Glauert factor and uses it to improve symbolic-regression discovery of the Karman-Tsien formula). The central claim is that the pipeline can find the low-dimensional intrinsic parameters of a physical system and can extract multiple parameter combinations simultaneously, overcoming limitations of power-law-only methods and single-branch symbolic-regression approaches.

Significance. If the central claims hold, Hi-π would be a useful, interpretable tool for data-driven dimensional analysis, particularly because it handles multiple dimensionless groups and nonlinear parameter combinations without a power-law ansatz. The mathematical examples are well designed and the use of external Rayleigh-Bénard and Nikuradse pipe-flow data gives the application section a realistic character. However, the paper's load-bearing assertions rest on two points that are currently not established: the claimed independence of the results from the arbitrary dimensionless-basis choice, and the quantitative reliability of the physical validations. The manuscript also does not provide code, data, or a precise definition of the success metrics used in the symbolic-regression comparisons, which limits reproducibility. The idea is coherent and the mathematical benchmarks appear to verify the implementation, but the physical claims need stronger evidence before the method can be accepted as a discoverer of intrinsic dimensionless parameters.

major comments (4)
  1. [§3.3, Eq. (18), Fig. 7] The central claim that Hi-π discovers 'intrinsic' dimensionless parameters requires that the output be independent of the arbitrarily selected dimensionless basis vectors w_b, but this is only asserted ('you can also select other dimensional index matrices w_b, and the final result is the same') and is neither proved nor systematically demonstrated. In log space, a change of basis is a unimodular integer transformation s' = A s, and while the monomial span is invariant in the exact infinite-data limit, the actual pipeline uses stochastic PySR, finite samples, and a manually selected polynomial order, so the order-loss trade-off can in principle favor different coordinate expressions for different bases. Please provide either a proof under the stated assumptions or an ablation study varying w_b over multiple random seeds for the mathematical, pipe-flow, and Rayleigh-Bénard cases, reporting the extracted combinations and test errors.
  2. [§3.2, Fig. 6] The Rayleigh-Bénard validation is not quantitatively assessable. The text states that 'incompatible transition state data' were deleted and that the Prandtl range was used to split datasets, but it does not report the resulting sample sizes, the exclusion criteria, the exact symbolic expressions returned by Hi-π, or how those expressions were identified as the Rayleigh and Prandtl numbers. Figure 6 shows prediction comparisons without numerical errors, error bars, or repeated-run variability. The authors should report the discovered expressions in a table, describe the identification procedure, and give quantitative metrics such as RMSE and R² for interpolation and extrapolation for both Hi-π and PyDimension.
  3. [§3.1, Fig. 4] The claim that Hi-π outperforms SFL on multi-parameter examples lacks a defined success criterion. The paper refers to 'extraction accuracy' and shows qualitative results, but it does not define how an extracted expression is judged correct (exact string match, symbolic equivalence after simplification, or numerical tolerance), how many repeated trials were used, or the per-example success rates. Without these details, the comparison and the claimed robustness to noise cannot be independently evaluated. Please specify the metric, the number of random seeds, and the per-example success rates for both methods.
  4. [§3.4, Fig. 9] The knowledge-discovery comparison reports accuracy rates (e.g., 70% for Hi-π and failure for PySR) without defining how the symbolic expressions are compared with the target formula, the noise level, or the number of trials. This is a load-bearing claim because it supports the paper's conclusion that Hi-π helps discover hierarchical expressions. Please define the accuracy metric, the data-generation noise, the trial count, and provide representative discovered expressions for both the Prandtl-Glauert and Karman-Tsien cases.
minor comments (6)
  1. [Throughout] The name 'Rayleigh-Bernard' should be written as 'Rayleigh-Bénard' in the abstract, the introduction, and Section 3.2.
  2. [§1, references [19] and [21]] The sentence 'Saha et al. proposed HiDeNN' is cited as reference [19], but reference [19] is the paper by Evangelou et al.; the HiDeNN paper appears to be reference [21]. Please correct this citation mismatch.
  3. [Eq. (10)] Equation (10) uses the symbol k for thermal diffusivity while the surrounding text uses κ; please unify the notation.
  4. [§3.3] The text refers to 'DimenisonNet'; this appears to be a typo for 'DimensionNet', and the cited reference [21] is listed as HiDeNN, so the terminology and reference need to be aligned.
  5. [§3.2, iterative strategy] The iterative strategy for determining the number of dimensionless parameter combinations is described only in prose at the end of Section 3.2; a pseudocode or algorithm box would substantially improve reproducibility.
  6. [Data availability] The data availability statement says data will be made available on request; given the stochastic nature of the symbolic-regression search, depositing the code and datasets would materially strengthen the paper.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: Hi-π's extracted groups are selected by a polynomial-fit objective and validated on external data; the unproved basis-independence assertion is an assumption, not a circular reduction.

full rationale

The claimed derivation chain is not circular. Hi-π selects dimensionless groups by optimizing the polynomial-fit loss (Eq. 1) over symbolic expressions of the intermediate Buckingham-Pi variables (Eqs. 10 and 19); the extracted groups Ra, Pr, Re, ε/D, and C_p0/(1-M^2)^{1/2} are outputs of that optimization, not inputs. The paper validates these outputs against data sources external to the fitting procedure (refs. 29-31 for Rayleigh-Bénard, ref. 33 for pipe flow, and the analytic Karman-Tsien benchmark for compressibility), and the prediction comparisons use held-out training/test splits. The only self-citation, SFL [23], is used as a comparison baseline and is not load-bearing for the core claim. The basis-independence assertion in the Figure 7 caption ('You can also select other dimensional index matrices w_b, and the final result is the same') is unsupported and is a correctness/validation risk, but an unproved invariance is not a reduction of the method's output to its input by construction. Therefore no circular step can be exhibited.

Assumptions & free parameters 4 free parameters · 5 assumptions · 0 invented entities

The method relies on standard dimensional analysis, smoothness and low-dimensional manifold assumptions for the output map, and the quality of external experimental datasets. No new physical particles, forces, or conserved quantities are introduced.

free parameters (4)
  • Polynomial mapping order = 4 (selected by order-loss elbow rule; order 5 used in math examples)
    The extracted parameter combination depends on the degree of the polynomial in the loss function. The paper selects order 4 for pipe flow and compressibility examples based on an underfitting/overfitting heuristic rather than a principled criterion.
  • Number of dimensionless parameter combinations n = 1 to 3 depending on example, determined iteratively
    The number of branches or parameter combinations is an input to the method. It is set to 1, 2, or 3 for the mathematical examples and determined by trial for the physical examples.
  • Initial dimensionless basis vectors w_b = Specific vectors in Eqs. (9) and (18)
    The Buckingham Pi step has infinitely many valid bases. The chosen basis changes the search space of symbolic regression, and the paper asserts basis independence without proof.
  • PySR hyperparameters = Not fully specified
    Population size, iterations, mutation rates, and selection pressure are not reported for the physics examples, so the success of the search may depend on unstated tuning.
assumptions (5)
  • standard math Buckingham Pi theorem gives a complete dimensional reduction, and the chosen dimensionless basis s is physically sufficient.
    Invoked in Step 1 and used in Eqs. (7)-(10) and (14)-(19) to reduce the input space before symbolic regression.
  • domain assumption The output dimensionless quantity Pi is a smooth function F of a small number of dimensionless parameter combinations pi_i, representable by a low-degree polynomial in the searched region.
    The polynomial mapping layer and the loss function in Eq. (1) assume this smooth and polynomial-representable relationship.
  • domain assumption A low-dimensional manifold exists in the high-dimensional dimensionless input space.
    The core premise of the supervised dimensionality-reduction framing in Section 1 and Eq. (11).
  • domain assumption The experimental data from references [29-31] are accurate, and the exclusion of "incompatible transition state data" does not bias the result.
    Section 3.2 describes data collection and filtering, but no criterion for the exclusion is given, so the filtered dataset is assumed to represent the intended physics.
  • domain assumption For synthetic examples, the Karman-Tsien and Prandtl-Glauert formulas exactly represent the target physical relation.
    Section 3.4 generates synthetic data from these formulas, so the benchmark assumes the formulas are the ground truth.

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Cite this review

Pith. "Pith review of Hierarchical Dimensionless Learning (Hi-{\pi}): A physics-data hybrid-driven approach for discovering dimensionless parameter combinations." pith.science (2026). https://pith.science/paper/PCZGSQ2A

@misc{pith2026250718332,
  author       = {Pith},
  title        = {Pith review of: Hierarchical Dimensionless Learning (Hi-\pi): A physics-data hybrid-driven approach for discovering dimensionless parameter combinations},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/PCZGSQ2A}},
  note         = {Machine review of arXiv:2507.18332}
}
read the original abstract

Dimensional analysis provides a universal framework for reducing physical complexity and reveal inherent laws. However, its application to high-dimensional systems still generates redundant dimensionless parameters, making it challenging to establish physically meaningful descriptions. Here, we introduce Hierarchical Dimensionless Learning (Hi-{\pi}), a physics-data hybrid-driven method that combines dimensional analysis and symbolic regression to automatically discover key dimensionless parameter combination(s). We applied this method to classic examples in various research fields of fluid mechanics. For the Rayleigh-B\'enard convection, this method accurately extracted two intrinsic dimensionless parameters: the Rayleigh number and the Prandtl number, validating its unified representation advantage across multiscale data. For the viscous flows in a circular pipe, the method automatically discovers two optimal dimensionless parameters: the Reynolds number and relative roughness, achieving a balance between accuracy and complexity. For the compressibility correction in subsonic flow, the method effectively extracts the classic compressibility correction formulation, while demonstrating its capability to discover hierarchical structural expressions through optimal parameter transformations.

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Works this paper leans on

38 extracted references · 37 canonical work pages

  1. [1]

    Scientific discovery in the age of artificial intelligence[J]

    Wang H, Fu T, Du Y , et al. Scientific discovery in the age of artificial intelligence[J]. Nature, 2023, 620(7972): 47-60

  2. [2]

    Machine learning for fluid mechanics[J]

    Brunton S L, Noack B R, Koumoutsakos P. Machine learning for fluid mechanics[J]. Annual review of fluid mechanics, 2020, 52(1): 477-508

  3. [3]

    Prospect of artificial intelligence empowered fluid mechanics[J]

    Zhang W, Kou J Q, Liu Y . Prospect of artificial intelligence empowered fluid mechanics[J]. Acta Aeronautica et Astronautica Sinica, 2021, 42(4): 524689

  4. [4]

    On physically similar systems; illustrations of the use of dimensional equations[J]

    Buckingham E. On physically similar systems; illustrations of the use of dimensional equations[J]. Physical review, 1914, 4(4): 345

  5. [5]

    Data-driven dimensional analysis: algorithms for unique and relevant dimensionless groups

    Constantine P G, del Rosario Z, Iaccarino G. Data -driven dimensional analysis: algorithms for unique and relevant dimensionless groups[J]. arXiv preprint arXiv:1708.04303, 2017

  6. [6]

    Data-driven discovery of dimensionless numbers and governing laws from scarce measurements[J]

    Xie X, Samaei A, Guo J, et al. Data-driven discovery of dimensionless numbers and governing laws from scarce measurements[J]. Nature communications, 2022, 13(1): 7562

  7. [7]

    Deep learning[M]

    Goodfellow I, Bengio Y , Courville A, et al. Deep learning[M]. Cambridge: MIT press, 2016

  8. [8]

    Artificial intelligence in physical sciences: Symbolic regression trends and perspectives[J]

    Angelis D, Sofos F, Karakasidis T E. Artificial intelligence in physical sciences: Symbolic regression trends and perspectives[J]. Archives of Computational Methods in Engineering, 2023, 30(6): 3845-3865

Show all 38 references
  1. [9]

    Interpretable scientific discovery with symbolic regression: a review[J]

    Makke N, Chawla S. Interpretable scientific discovery with symbolic regression: a review[J]. Artificial Intelligence Review, 2024, 57(1): 2

  2. [10]

    Scaling laws from statistical data and dimensional analysis

    Mendez P F, Ordonez F. Scaling laws from statistical data and dimensional analysis. Journal of Applied Mechanics, 2005, 72: 648–657

  3. [11]

    Active subspace methods in theory and practice: applications to kriging surfaces[J]

    Constantine P G, Dow E, Wang Q. Active subspace methods in theory and practice: applications to kriging surfaces[J]. SIAM Journal on Scientific Computing, 2014, 36(4): A1500-A1524

  4. [12]

    Data-driven dimensional analysis of heat transfer in irradiated particle-laden turbulent flow[J]

    Jofre L, del Rosario Z R, Iaccarino G. Data-driven dimensional analysis of heat transfer in irradiated particle-laden turbulent flow[J]. International Journal of Multiphase Flow, 2020, 125: 103198

  5. [13]

    Clustering dimensionless learning for multiple -physical-regime systems[J]

    Zhang L, Xu Z, Wang S, et al. Clustering dimensionless learning for multiple -physical-regime systems[J]. Computer Methods in Applied Mechanics and Engineering, 2024, 420: 116728

  6. [14]

    Artificial neural network based response surface for data -driven dimensional analysis[J]

    Xu Z, Zhang X, Wang S, et al. Artificial neural network based response surface for data -driven dimensional analysis[J]. Journal of Computational Physics, 2022, 459: 111145. 25

  7. [15]

    Data -driven discovery of self -similarity using neural networks[J]

    Watanabe R, Ishii T, Hirono Y , et al. Data -driven discovery of self -similarity using neural networks[J]. Physical Review E, 2025, 111(2): 024301

  8. [16]

    FIND: A Framework for Discovering Formulas in Data[C]//Proceedings of the AAAI Conference on Artificial Intelligence

    Xiao T, Cheng Y , Suo J. FIND: A Framework for Discovering Formulas in Data[C]//Proceedings of the AAAI Conference on Artificial Intelligence. 2025, 39(20): 21653-21660

  9. [17]

    Dimensionless learning based on information[J]

    Yuan Y , Lozano-Durán A. Dimensionless learning based on information[J]. arxiv preprint arxiv:2504.03927, 2025

  10. [18]

    Mutual -information-based dimensional learning: Objective algorithms for identification of relevant dimensionless quantities[J]

    Zhang L, He G. Mutual -information-based dimensional learning: Objective algorithms for identification of relevant dimensionless quantities[J]. Computer Methods in Applied Mechanics and Engineering, 2025, 440: 117922

  11. [19]

    On the parameter combinations that matter and on those that do not: data -driven studies of parameter (non) identifiability[J]

    Evangelou N, Wichrowski N J, Kevrekidis G A, et al. On the parameter combinations that matter and on those that do not: data -driven studies of parameter (non) identifiability[J]. PNAS nexus, 2022, 1(4): pgac154

  12. [20]

    Dimensionally consistent learning with Buckingham Pi[J]

    Bakarji J, Callaham J, Brunton S L, et al. Dimensionally consistent learning with Buckingham Pi[J]. Nature Computational Science, 2022, 2(12): 834-844

  13. [21]

    Hierarchical deep learning neural network (HiDeNN): an artificial intelligence (AI) framework for computational science and engineering[J]

    Saha S, Gan Z, Cheng L, et al. Hierarchical deep learning neural network (HiDeNN): an artificial intelligence (AI) framework for computational science and engineering[J]. Computer Methods in Applied Mechanics and Engineering, 2021, 373: 113452

  14. [22]

    Adaptive space transformation: An invariant based method for predicting aerodynamic coefficients of hypersonic vehicles[J]

    Luo C, Hu Z, Zhang S L, et al. Adaptive space transformation: An invariant based method for predicting aerodynamic coefficients of hypersonic vehicles[J]. Engineering Applications of Artificial Intelligence, 2015, 46: 93-103

  15. [23]

    Scaling Function Learning: A sparse aerodynamic data reconstruction method for generalizing aircraft shapes[J]

    Lin H, Wang X, Zhang W. Scaling Function Learning: A sparse aerodynamic data reconstruction method for generalizing aircraft shapes[J]. arXiv preprint arXiv:2411.08662, 2024

  16. [24]

    Distilling free-form natural laws from experimental data[J]

    Schmidt M, Lipson H. Distilling free-form natural laws from experimental data[J]. Science, 2009, 324(5923): 81-85

  17. [25]

    Gene expression programming: a new adaptive algorithm for solving problems[J]

    Ferreira C. Gene expression programming: a new adaptive algorithm for solving problems[J]. arXiv preprint cs/0102027, 2001

  18. [26]

    Interpretable machine learning for science with PySR and SymbolicRegression

    Cranmer M. Interpretable machine learning for science with PySR and SymbolicRegression. jl[J]. arXiv preprint arXiv:2305.01582, 2023

  19. [27]

    Global sensitivity indices for nonlinear mathematical models and their Monte Carlo estimates[J]

    Sobol I M. Global sensitivity indices for nonlinear mathematical models and their Monte Carlo estimates[J]. Mathematics and computers in simulation, 2001, 55(1-3): 271-280

  20. [28]

    Rayleigh L. LIX. On convection currents in a horizontal layer of fluid, when the higher temperature is on the under side[J]. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, 1916, 32(192): 529-546

  21. [29]

    The influence of the cell inclination on the heat transport and large -scale circulation in liquid metal convection[J]

    Zwirner L, Khalilov R, Kolesnichenko I, et al. The influence of the cell inclination on the heat transport and large -scale circulation in liquid metal convection[J]. Journal of Fluid Mechanics, 2020, 884: A18

  22. [30]

    Turbulent Rayleigh –Bénard convection in gaseous and liquid He[J]

    Chavanne X, Chilla F, Chabaud B, et al. Turbulent Rayleigh –Bénard convection in gaseous and liquid He[J]. Physics of Fluids, 2001, 13(5): 1300-1320

  23. [31]

    Turbulent convection at high Rayleigh numbers and aspect ratio 4[J]

    Niemela J J, Sreenivasan K R. Turbulent convection at high Rayleigh numbers and aspect ratio 4[J]. Journal of Fluid Mechanics, 2006, 557: 411-422

  24. [32]

    Scaling in Rayleigh –Bénard convection[J]

    Lindborg E. Scaling in Rayleigh –Bénard convection[J]. Journal of Fluid Mechanics, 2023, 956: A34

  25. [33]

    Laws of flow in rough pipes[J]

    Nikuradse J. Laws of flow in rough pipes[J]. 1950

  26. [34]

    Reynolds O. XXIX. An experimental investigation of the circumstances which determine whether 26 the motion of water shall be direct or sinuous, and of the law of resistance in parallel channels[J]. Philosophical Transactions of the Royal society of London, 1883 (174): 935-982

  27. [35]

    Roughness effects in turbulent pipe flow[J]

    Shockling M A, Allen J J, Smits A J. Roughness effects in turbulent pipe flow[J]. Journal of Fluid Mechanics, 2006, 564: 267-285

  28. [36]

    EBOOK: Fundamentals of Aerodynamics (SI units)[M]

    Anderson J. EBOOK: Fundamentals of Aerodynamics (SI units)[M]. McGraw hill, 2011

  29. [37]

    Two -dimensional subsonic flow of compressible fluids[J]

    Tsien H S. Two -dimensional subsonic flow of compressible fluids[J]. Journal of spacecraft and rockets, 2003, 40(6): 983-991

  30. [38]

    AI Feynman: A physics -inspired method for symbolic regression[J]

    Udrescu S M, Tegmark M. AI Feynman: A physics -inspired method for symbolic regression[J]. Science Advances, 2020, 6(16): eaay2631

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Reviewed August 15, 2026 · model on record in the stance chip above.