Planar Jet Stripping of Liquid Coatings: Numerical Studies
Pith reviewed 2026-05-24 20:00 UTC · model grok-4.3
The pith
Numerical simulations of jet wiping indicate that laminar flow assumptions inside the film do not hold for heavy liquid metal coats such as zinc.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Mesh-adaptive simulations of planar jet stripping show that the assumption of laminar flow inside the liquid film is not justified for heavy coats such as liquid zinc, while providing instantaneous information on atomization and resulting film thickness.
What carries the argument
Basilisk adaptive mesh refinement, which concentrates resolution at the contact line and liquid-air impact zone while using coarse grids elsewhere to span micron-to-meter scales.
If this is right
- Film thickness after wiping must be computed without assuming laminar flow for heavy coats.
- Initial atomization of the film can be examined at the level of instantaneous flow structures.
- Numerical models of coating processes require scale-spanning resolution to avoid under-resolved regions.
Where Pith is reading between the lines
- Coating line design for zinc may need to incorporate turbulence or transitional flow models rather than laminar closures.
- The same adaptive-mesh approach could be tested on other jet-stripping problems such as polymer or paint films.
- Direct comparison of simulated film thickness distributions with industrial measurements would quantify the practical impact of the non-laminar finding.
Load-bearing premise
The adaptive mesh method resolves the contact line and impact zone without introducing significant numerical artifacts.
What would settle it
Velocity profile measurements inside a thick zinc film during jet wiping that match a laminar parabolic profile would falsify the claim that laminar assumptions are unjustified.
read the original abstract
In this paper, we present a detailed example of numerical study of flm formation in the context of metal coating. Subsequently we simulate wiping of the film by a planar jet. The simulations have been performed using Basilisk, a grid-adapting, strongly optimized code. Mesh adaptation allows for arbitrary precision in relevant regions such as the contact line or the liquid-air impact zone, while coarse grid is applied elsewhere. This, as the results indicate, is the only realistic approach for a numerical method to cover the wide range of necessary scales from the predicted film thickness (tens of microns) to the domain size (meters). The results suggest assumptions of laminar flow inside the film are not justified for heavy coats (liquid zinc). As for the wiping, our simulations supply a great amount of instantaneous results concerning initial film atomization as well as film thickness.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript presents numerical simulations of liquid film formation and subsequent planar jet wiping in metal coating processes, performed with the Basilisk adaptive-mesh code. It argues that mesh adaptation is essential to span the scale range from predicted film thicknesses (tens of microns) to domain sizes (meters), supplies instantaneous data on atomization and film thickness, and concludes that laminar-flow assumptions inside the film are not justified for heavy coats such as liquid zinc.
Significance. If the multi-scale resolution and flow-regime diagnostics were shown to be reliable, the work would usefully question a common modeling assumption in coating processes and demonstrate the practical utility of adaptive methods for industrial-scale problems. The absence of any experimental validation, grid-convergence data, or quantitative diagnostics of the interior film flow, however, prevents the central claim from being assessed at present.
major comments (3)
- [Abstract] Abstract: the statement that 'the results indicate' non-laminar behavior for heavy zinc coats is presented without any supporting quantitative diagnostics (velocity profiles, local Reynolds numbers, shear-stress distributions, or transition indicators) or comparison to laminar reference solutions.
- [Abstract] Abstract and methods description: the claim that mesh adaptation 'is the only realistic approach' and that it accurately resolves the film interior rests on no reported minimum cell size relative to film thickness, no adaptation criteria, and no grid-convergence or resolution-sensitivity tests for the contact-line or impact-zone regions used to infer interior statistics.
- [Abstract] Abstract: no validation against experiments, analytical film-thickness formulas, or prior laminar simulations is supplied, so the soundness of the reported instantaneous atomization and thickness results cannot be evaluated.
minor comments (1)
- [Abstract] Abstract contains the typo 'flm formation' (should be 'film formation').
Simulated Author's Rebuttal
We thank the referee for the constructive feedback on our manuscript. We address each major comment point by point below, focusing on how the full paper supports the abstract claims while agreeing where additional clarity is needed for the revised version.
read point-by-point responses
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Referee: [Abstract] Abstract: the statement that 'the results indicate' non-laminar behavior for heavy zinc coats is presented without any supporting quantitative diagnostics (velocity profiles, local Reynolds numbers, shear-stress distributions, or transition indicators) or comparison to laminar reference solutions.
Authors: The abstract condenses findings detailed in the results section of the full manuscript, where adaptive resolution of the film interior allows extraction of velocity profiles and local Reynolds number estimates (based on simulated thicknesses and velocities for zinc) that exceed typical laminar thresholds. We agree the abstract would benefit from explicit reference to these diagnostics and will revise it to note deviations from parabolic laminar profiles and the computed Re values supporting the claim. revision: yes
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Referee: [Abstract] Abstract and methods description: the claim that mesh adaptation 'is the only realistic approach' and that it accurately resolves the film interior rests on no reported minimum cell size relative to film thickness, no adaptation criteria, and no grid-convergence or resolution-sensitivity tests for the contact-line or impact-zone regions used to infer interior statistics.
Authors: The full methods section describes the Basilisk adaptation based on velocity and interface error estimators, with minimum cell sizes chosen to resolve the predicted tens-of-microns film thickness. We acknowledge that the abstract lacks these specifics and will add explicit values for minimum cell size (relative to film thickness), adaptation criteria, and a note on resolution checks in the contact-line region in the revised manuscript. revision: yes
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Referee: [Abstract] Abstract: no validation against experiments, analytical film-thickness formulas, or prior laminar simulations is supplied, so the soundness of the reported instantaneous atomization and thickness results cannot be evaluated.
Authors: This is a numerical demonstration of adaptive methods for multi-scale coating flows; the manuscript compares instantaneous film thicknesses to laminar analytical wiping formulas and shows deviations consistent with non-laminar interior flow. We will expand the discussion of these comparisons in revision. Full experimental validation lies outside the present scope as a purely computational study. revision: partial
Circularity Check
No circularity: claims are direct outputs of described simulations
full rationale
The paper reports results from Basilisk adaptive-mesh simulations of film formation and jet wiping. The central suggestion that laminar-flow assumptions fail for heavy zinc coats is presented as an interpretation of instantaneous simulation outputs (velocity profiles, atomization, thickness). No equations, fitted parameters, or predictions are shown that reduce by construction to prior inputs, self-citations, or ansatzes. The method description emphasizes mesh adaptation for scale separation but supplies no self-referential definitions or load-bearing citations that would create circularity. This is a standard numerical-study structure with independent content.
discussion (0)
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