REVIEW 4 major objections 4 minor 33 references
Experimental investigation of lift-up and instability of the viscous flow induced by a rotating cone-cylinder in an enclosure
T0 review · 4 major / 4 minor · reviewed 2026-08-07 · deepseek-v4-flash
Pith's one-line read A rotating cone-cylinder inside an enclosure produces an outward jet that lifts its viscous boundary layer off the wall, and the jet's axial position jumps from near the cone-cylinder junction to near the base once the rotational Reynolds…
desk verdict A credible, clearly presented experimental observation of a two-regime lift-up on a rotating cone-cylinder; the sharp switch is plausible but the quantitative critical Reynolds number is only bracketed. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The lift-up location is defined as the axial peak of the Reynolds number $Re_{v,\delta_\nu} = v\delta_\nu/\nu$ built on the axis-normal velocity $v$ and the diffusion length scale $\delta_\nu=\sqrt{\nu/\Omega}$, measured along the off-wall line $Y=0.48L$. This trace converts the planar flow into a one-dimensional profile whose peak marks the mutual upwash of the counter-rotating vortex pair, and the grouping of the profiles into two overlapping sets provides the evidence for two distinct flow regimes.
What would settle it
Repeat the PIV measurements at several off-wall heights $Y/L$ (for example 0.3, 0.4, 0.5, 0.6) and compare the axial peak of $Re_{v,\delta_\nu}$; if the peak location is not nearly constant across $Y/L$ near the critical Reynolds number, the two-regime claim loses support. Alternatively, a fully three-dimensional measurement (stereo-PIV or tomographic PIV) that checks the symmetry-plane assumption under the measured eccentricity would settle whether out-of-plane motion creates the apparent jump.
Extended reading notes
Core claim
In a closed box, the meridional flow driven by the slender cone and the opposite flow driven by the base disk collide on the cylinder section. Their collision creates a symmetry-plane outward jet that lifts the viscous boundary layer off the wall, much like the outward jets known in Taylor-Couette and spherical-Couette flows. Time-resolved images show counter-rotating Taylor vortices forming in the rotating boundary layer, being convected, and interacting in the lift-up region, which produces skewed velocity-fluctuation statistics. When the rotational Reynolds number $Re_b = R^2\Omega/\nu$ is below roughly $2\times10^3$, the lift-up sits at $X/L\approx0.3$; above $2\times10^3$–$2.5\times10^3$, the lift-up shifts to $X/L\approx0.58$. The paper attributes the shift to transition of the cone boundary layer, which energizes the near-wall flow and lets the corner flow push farther against the adverse pressure gradient.
Load-bearing premise
The lift-up location is read off a single off-wall horizontal line at $Y=0.48L$; if the peak position changes when a different line is chosen, or if slight model wobble (up to $0.005L$ eccentricity) displaces the measurement plane, the reported jump from $X/L\approx0.3$ to $\approx0.58$ could be an artifact of that choice rather than a genuine change in the flow.
Editorial extensions
If this is right
- The viscous influence of a rotating composite body in an enclosure extends far beyond the boundary-layer thicknesses known from isolated cones or cylinders, so estimates of mixing, drag, and heat transfer in such devices should account for the lift-up.
- The large-scale counter-rotating vortex pair localizes scalar transport inside the enclosure, producing non-uniform mixing that depends on the lift-up position.
- The observed jump in lift-up location could act as a macroscopic, non-intrusive signature of cone boundary-layer transition, measurable without close-wall instrumentation.
- Taylor vortices carried into the lift-up region produce intermittent extreme velocity fluctuations, which will affect any process that relies on steady near-wall conditions.
Reading between the lines
- If the lift-up location is controlled by the cone boundary-layer state, the critical Reynolds number should vary with cone half-angle, enclosure clearance, and junction curvature; a parametric study could turn the observed jump into a scaling law.
- The single-line criterion (peak at $Y=0.48L$) should be checked against other off-wall heights and against three-dimensional measurements, since a tilt or eccentricity of the measurement plane could shift the apparent peak.
- Because the lift-up resembles Couette-flow outward jets, the same vortex-pair mechanism may appear in other confined rotating geometries with two opposing meridional pressure gradients, such as rotor-stator systems with a central cone.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper reports two-component PIV measurements in the symmetry plane of a 15-degree half-angle cone-cylinder rotating inside a rectangular enclosure, at five rotation rates corresponding to Re_b = R^2 Omega/nu between 1178 and 3241. The mean flow fields show a cone-induced meridional flow towards the base and a base-disk-induced reverse flow that meet on the cylinder, lifting the rotating boundary layer away from the wall as an outward jet. Instantaneous vorticity fields show Taylor-vortex-like structures that are advected into the lift-up region, and PDFs of axial velocity fluctuations are presented to characterize unsteadiness. The central quantitative claim is that the lift-up location switches from X/L approximately 0.3 to X/L approximately 0.58 when Re_b crosses a critical value between 2e3 and 2.5e3, based on the peak of Re_{v,delta_nu} along the single line Y/L = 0.48 (Fig. 5) and on visual grouping of the PDF widths (Fig. 4).
Significance. If the reported regime switch is robust, the paper documents a new flow-organization feature for a composite rotating body in a confined domain, with potential consequences for mixing, transport, and surface heat transfer in applications such as stirring, boring, and rotating projectiles. The study has notable strengths: no parameters are fitted to the data, the Reynolds numbers used are standard definitions, and the mean lift-up and the large-scale counter-rotating vortex pair are clearly visible in the vector fields. The main significance, however, hinges on the quantitative identification of the critical Reynolds number and on the two-group classification of lift-up locations, and that evidence is currently based on a single off-wall measurement line and on two adjacent rotation-rate cases without uncertainty estimates.
major comments (4)
- [Section III, Fig. 5] The central claim of a critical switch in lift-up location is based on the peak of Re_{v,delta_nu} evaluated on a single line Y/L = 0.48. This line lies roughly 0.039 m from the cylinder surface, which is tens of viscous lengths delta_nu, so the profile tracks the upwash of the large-scale counter-rotating vortex pair rather than the lift-off of the rotating boundary layer itself. The wall separation point and the vortex-pair upwash line need not coincide, and their relative shift with Reynolds number is not established. Please show the axial peak location for several Y/L values, or use a near-wall criterion, to demonstrate that the 0.3-to-0.58 grouping is independent of the chosen radial coordinate.
- [Table 1 and Fig. 5(b)] The critical Reynolds number is bracketed by only two adjacent rotation rates, Re_b = 2030 (124 RPM) and Re_b = 2455 (150 RPM). No uncertainty estimates are reported for rotation speed, velocity, or peak location, so the apparent discontinuity between these two cases could be within measurement scatter. Please report repeatability and error bars on X/L_peak and, if possible, add intermediate rotation rates to establish the bracketing of Re_b,c.
- [Section III, Fig. 4] The two-group classification is based on visual inspection of peak-normalised PDFs, with the widest distribution reported at X/L approximately 0.3 +/- 0.05 for cases at and below 124 RPM and at X/L approximately 0.58 for cases at and above 150 RPM. A quantitative criterion, such as the axial location of maximum variance or skewness with confidence intervals, is needed to distinguish two discrete groups from a continuous downstream shift of the fluctuation maximum.
- [Section II and Section III] The velocity measurements are 2C PIV in the symmetry plane. In a flow with a strong azimuthal, out-of-plane component and with Taylor vortices, the measured in-plane v field can be biased by out-of-plane motion and by slight laser-sheet misalignment; the reported model eccentricity of up to 0.005L could also break the symmetry. Please quantify the sensitivity of the lift-up peak location to these effects, or justify that they are negligible at the reported level.
minor comments (4)
- [Introduction] The text contains typographical errors, including 'V on Karman' in the introduction and the incomplete author field in reference 30 ('A.J.P.'); please proofread the manuscript carefully.
- [Fig. 5(a)] Figure 5(a) should label the vertical axis explicitly and mark the five cases consistently with Table 1, so that the reader can identify which profile corresponds to which rotation rate.
- [Section II] The statement that the enclosure is 'sufficiently large' is not quantified; reporting the ratio of enclosure dimensions to model radius or the blockage ratio would make the boundary-condition argument more precise.
- [Section II and III] Since the fluctuation statistics are central to Fig. 4, please report a convergence check on the number of image pairs (600) to show that the PDF shapes and their peak locations are converged.
Circularity Check
No significant circularity: the lift-up location is a direct PIV-based observable, the critical Reynolds number is read from a discrete jump between measured cases, and the self-citations are interpretive rather than load-bearing.
full rationale
This paper is a purely experimental PIV study, and the derivation chain is data-to-interpretation rather than theory-to-prediction. The lift-up location is operationally defined as the axial position of the peak of Re_{v,delta_nu}=v*delta_nu/nu measured on the single line Y=0.48L (Section III, Figure 5a). This quantity is simply the measured axis-normal velocity normalized by the viscous scale delta_nu=sqrt(nu/Omega); no parameter is fitted to the data, and the peak location is a direct observable, not a constructed prediction. The two-group classification (X/L~0.3 versus X/L~0.58) is corroborated by a second, independent diagnostic: the width of the axial-velocity fluctuation probability density function in Figure 4 is widest at the same two axial locations for the same cases. The claimed critical Reynolds number Re_b,c in the range 2e3-2.5e3 is inferred from the discrete jump between case 3 (124 RPM, Re_b=2030) and case 4 (150 RPM, Re_b=2455), and is not obtained by fitting any curve or parameter. The only self-citations are to prior work by co-author Tambe (references 16 and 19-21), used to support the interpretive mechanism that boundary-layer transition on the rotating cone delays the lift-up by enhancing near-wall momentum; however, the paper itself marks this explanation as 'expected' and states that 'this aspect needs further investigation with the close-wall measurements on the rotating cone-cylinder junction.' Thus the central empirical claim does not depend on those citations being correct. No equation in the paper is constructed so that an output equals an input by definition, and no fitted quantity is renamed as a prediction. The score of 1 reflects at most a minor interpretive self-citation that is explicitly acknowledged as requiring further investigation and is not load-bearing for the reported measurements.
Assumptions & free parameters
assumptions (4)
- domain assumption The PIV measurements faithfully resolve the mean and fluctuating velocity fields in the symmetry plane, with 1 micron smoke particles following the flow.
- domain assumption The enclosure is large enough that enclosure-wall boundary layers do not merge with the rotating-surface boundary layers, yet the enclosure still sets up the large-scale counter-rotating vortex pair.
- domain assumption The peak in Re_{v,delta_nu} along the off-wall line Y=0.48L marks the lift-up (mutual upwash) location.
- domain assumption The transition Reynolds number range for an isolated rotating cone in still fluid (Kobayashi and Izumi, Re about 1e3 to 4.9e3) is relevant to interpreting the present enclosed cone-cylinder flow.
Cite this review
Pith. "Pith review of Experimental investigation of lift-up and instability of the viscous flow induced by a rotating cone-cylinder in an enclosure." pith.science (2026). https://pith.science/paper/XBFQDQIB
@misc{pith2026250523076,
author = {Pith},
title = {Pith review of: Experimental investigation of lift-up and instability of the viscous flow induced by a rotating cone-cylinder in an enclosure},
year = {2026},
howpublished = {\url{https://pith.science/paper/XBFQDQIB}},
note = {Machine review of arXiv:2505.23076}
}
abstract
This paper probes into the flow induced by a rotating cone-cylinder model in an enclosure. Two component particle image velocimetry measurements in the symmetry plane reveal that the rotating cone-cylinder causes an outward jet on the cylinder section, which lifts the rotating boundary layers away from the wall. A large-scale counter-rotating vortex pair sets up with its mutual upwash aligned with the lift-up region. Furthermore, the centrifugal instability induces Taylor vortices in the rotating boundary layer, which are convected by the mean flow field and are lifted away from the surface, causing a high standard deviation. The lift-up phenomenon shows two preferred axial locations: below a critical Reynolds number $Re_{b,c}$, the lift-up occurs close to the cone-cylinder junction, and for Reynolds number higher than $Re_{b,c}$ lift-up is pushed away from the cone-cylinder junction, towards the model base. The value of the critical Reynolds number $Re_{b,c}$ lies within $2 \times 10^3-2.5 \times 10^3$ for the investigated cases.
Figures
Figures from the paper (3 more)
Reference graph
Works this paper leans on
-
[1]
author author D. Zhao , author Y. Zhang , author M. Bi , author X. Zheng , author X. Zhong , \ and\ author S. Zhang ,\ title title The aerodynamic characteristics of a rotating cylinder based on large-eddy simulations , \ @noop journal journal Journal of Marine Science and Engineering \ volume 11 ,\ pages 1162 ( year 2023 ) NoStop
work page 2023
-
[2]
author author A. Suwono ,\ title title Laminar boundary layer flows near rotating bodies of revolution of arbitrary contour , \ @noop journal journal Acta Mechanica \ volume 39 ,\ pages 51--63 ( year 1981 ) NoStop
work page 1981
-
[3]
author author N. Rott \ and\ author W. Lewellen ,\ title title Boundary layers in rotating flows , \ in\ @noop booktitle Applied Mechanics: Proceedings of the Eleventh International Congress of Applied Mechanics Munich (Germany) 1964 \ ( organization Springer ,\ year 1966 )\ pp.\ pages 1030--1036 NoStop
work page 1964
-
[4]
author author N. Tanasheva , author L. Chirkova , author A. Dyusembaeva , \ and\ author K. Sadenova ,\ title title Aerodynamic characteristics of a rotating cylinder in the form of a truncated cone , \ @noop journal journal Journal of Engineering Physics and Thermophysics \ volume 93 ,\ pages 551--555 ( year 2020 ) NoStop
work page 2020
-
[5]
author author G. Jim \'e nez , author A. Verdeza , author A. J. \ Orozco-Jimenez , author A. Bula , author P. Perreault , \ and\ author A. Gonzalez-Quiroga ,\ title title Swirling fluidized bed hydrodynamics: Experimental and angular momentum-based assessment , \ @noop journal journal Chemical Engineering Journal \ volume 505 ,\ pages 158867 ( year 2025 ) NoStop
work page 2025
-
[6]
author author P. H. \ Alfredsson , author K. Kato , \ and\ author R. Lingwood ,\ title title Flows over rotating disks and cones , \ @noop journal journal Annual Review of Fluid Mechanics \ volume 56 ,\ pages 45--68 ( year 2024 ) NoStop
work page 2024
-
[7]
Von K \'a rm \'a n ,\ title title Uber laminare und turbulente reibung , \ @noop journal journal Z
author author T. Von K \'a rm \'a n ,\ title title Uber laminare und turbulente reibung , \ @noop journal journal Z. Angew. Math. Mech. \ volume 1 ,\ pages 233--252 ( year 1921 ) NoStop
work page 1921
-
[8]
author author G. I. \ Taylor ,\ title title Viii. stability of a viscous liquid contained between two rotating cylinders , \ @noop journal journal Philosophical Transactions of the Royal Society of London. Series A, Containing Papers of a Mathematical or Physical Character \ volume 223 ,\ pages 289--343 ( year 1923 ) NoStop
work page 1923
Show all 33 references
-
[9]
Gregory , author J
author author N. Gregory , author J. T. \ Stuart , \ and\ author W. Walker ,\ title title On the stability of three-dimensional boundary layers with application to the flow due to a rotating disk , \ @noop journal journal Philosophical Transactions of the Royal Society of Lond...
1955
-
[10]
Kobayashi , author Y
author author R. Kobayashi , author Y. Kohama , \ and\ author C. Takamadate ,\ title title Spiral vortices in boundary layer transition regime on a rotating disk , \ @noop journal journal Acta Mechanica \ volume 35 ,\ pages 71--82 ( year 1980 ) NoStop
1980
-
[11]
Kobayashi , author Y
author author R. Kobayashi , author Y. Kohama , \ and\ author M. Kurosawa ,\ title title Boundary-layer transition on a rotating cone in axial flow , \ @noop journal journal Journal of Fluid Mechanics \ volume 127 ,\ pages 341--352 ( year 1983 ) NoStop
1983
-
[12]
Kohama ,\ title title Study on boundary layer transition of a rotating disk , \ @noop journal journal Acta Mechanica \ volume 50 ,\ pages 193--199 ( year 1984 ) NoStop
author author Y. Kohama ,\ title title Study on boundary layer transition of a rotating disk , \ @noop journal journal Acta Mechanica \ volume 50 ,\ pages 193--199 ( year 1984 ) NoStop
1984
-
[13]
Hussain , author S
author author Z. Hussain , author S. J. \ Garrett , author S. Stephen , \ and\ author P. T. \ Griffiths ,\ title title The centrifugal instability of the boundary-layer flow over a slender rotating cone in an enforced axial free stream , \ @noop journal journal Journal of Flui...
2016
-
[14]
author author S. J. \ Garrett , author Z. Hussain , \ and\ author S. Stephen ,\ title title The cross-flow instability of the boundary layer on a rotating cone , \ @noop journal journal Journal of Fluid Mechanics \ volume 622 ,\ pages 209--232 ( year 2009 ) NoStop
2009
-
[15]
Kato , author A
author author K. Kato , author A. Segalini , author P. Alfredsson , \ and\ author R. Lingwood ,\ title title Instability and transition in the boundary layer driven by a rotating slender cone , \ 10.1017/jfm.2021.216 journal journal Journal of Fluid Mechanics \ volume 915 ,\ p...
2021 doi
-
[16]
Tambe , author K
author author S. Tambe , author K. Kato , \ and\ author Z. Hussain ,\ title title Görtler-number-based scaling of boundary-layer transition on rotating cones in axial inflow , \ 10.1017/jfm.2024.379 journal journal Journal of Fluid Mechanics \ volume 987 ,\ pages R3 ( year 202...
2024 doi
-
[17]
author author M. Miller ,\ title title Wind tunnel measurements of the magnus induced surface pressures on a spinning projectile in the transonic speed regime , \ in\ @noop booktitle Applied Aerodynamics Conference \ ( year 1983 )\ p.\ pages 1838 NoStop
1983
-
[18]
author author W. B. \ Sturek ,\ title title Boundary-layer studies on spinning bodies of revolution , \ @noop \ ( year 1973 ) NoStop
1973
-
[19]
Tambe , author F
author author S. Tambe , author F. Schrijer , author A. Gangoli Rao , \ and\ author L. Veldhuis ,\ title title Boundary layer instability over a rotating slender cone under non-axial inflow , \ 10.1017/jfm.2020.990 journal journal Journal of Fluid Mechanics \ volume 910 ,\ pag...
2020 doi
-
[20]
Tambe , author F
author author S. Tambe , author F. Schrijer , author A. G. \ Rao , \ and\ author L. Veldhuis ,\ title title An experimental method to investigate coherent spiral vortices in the boundary layer over rotating bodies of revolution , \ @noop journal journal Experiments in Fluids \...
2019
-
[21]
Tambe , author F
author author S. Tambe , author F. Schrijer , author L. Veldhuis , \ and\ author A. Gangoli Rao ,\ title title Spiral instability modes on rotating cones in high-reynolds number axial flow , \ 10.1063/5.0083564 journal journal Physics of Fluids \ volume 34 ,\ pages 034109 ( ye...
-
[22]
Chen \ and\ author D
author author C. Chen \ and\ author D. K. \ Christensen ,\ title title Stability of flow induced by an impulsively started rotating cylinder , \ @noop journal journal Physics of Fluids \ volume 10 ,\ pages 1845--1846 ( year 1967 ) NoStop
1967
-
[23]
Honji ,\ title title Streaked flow around an oscillating circular cylinder , \ @noop journal journal Journal of Fluid Mechanics \ volume 107 ,\ pages 509--520 ( year 1981 ) NoStop
author author H. Honji ,\ title title Streaked flow around an oscillating circular cylinder , \ @noop journal journal Journal of Fluid Mechanics \ volume 107 ,\ pages 509--520 ( year 1981 ) NoStop
1981
-
[24]
Mittal \ and\ author B
author author S. Mittal \ and\ author B. Kumar ,\ title title Flow past a rotating cylinder , \ 10.1017/S0022112002002938 journal journal Journal of Fluid Mechanics \ volume 476 ,\ pages 303–334 ( year 2003 ) NoStop
2003 doi
-
[25]
Rao , author J
author author A. Rao , author J. S. \ Leontini , author M. C. \ Thompson , \ and\ author K. Hourigan ,\ title title Three-dimensionality in the wake of a rapidly rotating cylinder in uniform flow , \ 10.1017/jfm.2013.362 journal journal Journal of Fluid Mechanics \ volume 730 ...
2013 doi
-
[26]
Kageyama , author H
author author A. Kageyama , author H. Ji , author J. Goodman , author F. Chen , \ and\ author E. Shoshan ,\ title title Numerical and experimental investigation of circulation in short cylinders , \ 10.1143/JPSJ.73.2424 journal journal Journal of the Physical Society of Japan ...
-
[27]
Bühler , author J
author author K. Bühler , author J. E. R. \ Coney , author M. Wimmer , \ and\ author J. Zierep ,\ title title Advances in taylor vortex flow: A report on the fourth taylor vortex flow working party meeting , \ @noop journal journal Acta Mechanica \ volume 62 ( year 1986 ) NoStop
1986
-
[28]
von Stamm , author T
author author J. von Stamm , author T. Buzug , \ and\ author G. Pfister ,\ title title Frequency locking in axisymmetric taylor-couette flow , \ https://doi.org/10.1016/0375-9601(94)91279-3 journal journal Physics Letters A \ volume 194 ,\ pages 173--178 ( year 1994 ) NoStop
-
[29]
author author P. S. \ Marcus \ and\ author L. S. \ Tuckerman ,\ title title Simulation of flow between concentric rotating spheres. part 1. steady states , \ 10.1017/S0022112087003069 journal journal Journal of Fluid Mechanics \ volume 185 ,\ pages 1–30 ( year 1987 ) NoStop
-
[30]
author author A. J.P. , author M. Sharma , author A. Sameen , \ and\ author V. Narayanan ,\ title title Bifurcations in narrow-gap spherical couette flow , \ 10.1017/jfm.2025.163 journal journal Journal of Fluid Mechanics \ volume 1007 ,\ pages A64 ( year 2025 ) NoStop
2025 doi
-
[31]
Kobayashi \ and\ author H
author author R. Kobayashi \ and\ author H. Izumi ,\ title title Boundary-layer transition on a rotating cone in still fluid , \ @noop journal journal Journal of Fluid Mechanics \ volume 127 ,\ pages 353--364 ( year 1983 ) NoStop
1983
-
[32]
Imayama , author P
author author S. Imayama , author P. H. \ Alfredsson , \ and\ author R. J. \ Lingwood ,\ title title A new way to describe the transition characteristics of a rotating-disk boundary-layer flow , \ 10.1063/1.3696020 journal journal Physics of Fluids \ volume 24 ,\ pages 031701 ...
-
[33]
Bhoraniya \ and\ author V
author author R. Bhoraniya \ and\ author V. Narayanan ,\ title title Global stability analysis of axisymmetric boundary layer on a rotating circular cylinder , \ https://doi.org/10.1016/j.ijheatfluidflow.2023.109241 journal journal International Journal of Heat and Fluid Flow ...
2023
Reviewed August 7, 2026 · model on record in the stance chip above.
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