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arxiv: 2607.02310 · v1 · pith:JXDHJMAQnew · submitted 2026-07-02 · ⚛️ physics.flu-dyn · cond-mat.stat-mech

Pressure-drop localization and momentum insulation in liquid-gas coexistence Poiseuille flow

Naoko Nakagawa , Shin-ichi Sasa This is my paper

Pith reviewed 2026-07-03 04:48 UTC · model grok-4.3

classification ⚛️ physics.flu-dyn cond-mat.stat-mech
keywords Poiseuille flowliquid-gas coexistencepressure-drop localizationmomentum insulationinterfacial coolingtwo-phase flowadiabatic plates
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The pith

In liquid-gas coexistence Poiseuille flow, the pressure difference concentrates at the interface and sharply reduces the particle current.

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

The paper examines pressure-driven flow of a one-component fluid between adiabatic plates where liquid and gas phases coexist. It combines Poiseuille flow and Fourier heat conduction in the bulk regions with particle and energy conservation to derive the governing equations. Extremely small dimensionless parameters emerge from the squared ratio of microscopic to macroscopic lengths. Under weak driving with macroscopic phase regions, these parameters force the pressure drop to localize almost entirely at the interface. The resulting particle current is much smaller than in single-phase flow, and equal-temperature reservoirs produce interfacial cooling from the residual current.

Core claim

From the bulk equations of Poiseuille flow and Fourier heat conduction together with particle and energy conservation, extremely small dimensionless parameters A^L and A^G are identified for coexistence Poiseuille flow. In weak driving with macroscopic liquid and gas regions, the pressure difference is concentrated across the interfacial region, and the ordinary Poiseuille particle current is strongly reduced. For equal-temperature reservoirs, this residual particle current produces interfacial cooling.

What carries the argument

The extremely small dimensionless parameters A^L and A^G that arise from squared microscopic-to-macroscopic length ratios and enforce pressure-drop localization together with momentum insulation at the interface.

Load-bearing premise

The bulk liquid and gas regions obey Poiseuille flow profiles and Fourier heat conduction while particle number and energy are conserved across the entire system.

What would settle it

Measurement of the pressure profile in a channel with macroscopic liquid and gas regions that shows nearly the entire drop occurring inside the interfacial zone rather than distributed through the bulks.

Figures

Figures reproduced from arXiv: 2607.02310 by Naoko Nakagawa, Shin-ichi Sasa.

Figure 1
Figure 1. Figure 1: FIG. 1. Schematic setup of liquid-gas Poiseuille flow between [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Pressure profile in coexistence flow in the small- [PITH_FULL_IMAGE:figures/full_fig_p005_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. Schematic particle current for fixed ∆ [PITH_FULL_IMAGE:figures/full_fig_p006_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. Schematic temperature profile for interfacial cooling [PITH_FULL_IMAGE:figures/full_fig_p007_4.png] view at source ↗
read the original abstract

We study pressure-driven Poiseuille flow of a one-component fluid between adiabatic plates in liquid-gas coexistence. The analysis uses Poiseuille flow and Fourier heat conduction in the bulk regions together with particle and energy conservation. From these bulk equations, we identify extremely small dimensionless parameters $A^\mathrm{L}$ and $A^\mathrm{G}$ describing coexistence Poiseuille flow, whose smallness comes from squared microscopic-to-macroscopic length ratios. In weak driving with macroscopic liquid and gas regions, the pressure difference is concentrated across the interfacial region, and the ordinary Poiseuille particle current is strongly reduced. For equal-temperature reservoirs, this residual particle current produces interfacial cooling.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

0 major / 3 minor

Summary. The manuscript analyzes pressure-driven Poiseuille flow of a one-component fluid in liquid-gas coexistence between adiabatic plates. Applying standard Poiseuille flow and Fourier heat conduction in the bulk regions together with particle and energy conservation across the interface, it identifies the dimensionless parameters A^L and A^G whose smallness follows from squared microscopic-to-macroscopic length ratios. The central claims are that, under weak driving with macroscopic phase regions, the imposed pressure difference localizes at the interface (producing momentum insulation), the net particle current is strongly suppressed relative to single-phase Poiseuille flow, and equal-temperature reservoirs induce net interfacial cooling from the residual flux.

Significance. If the derivation holds, the work supplies a transparent, parameter-free explanation for pressure-drop localization and interfacial cooling that follows directly from scale separation and standard bulk constitutive relations. The explicit identification of A^L and A^G as O((l_micro/l_macro)^2) and the closure via conservation laws constitute a strength; the resulting predictions for current reduction and cooling are falsifiable and could inform microfluidic or heat-transfer applications involving two-phase coexistence.

minor comments (3)
  1. The abstract and introduction would benefit from a single sentence stating the numerical order of magnitude expected for A^L and A^G at typical laboratory channel widths (e.g., 100 µm–1 mm) to make the phrase 'extremely small' quantitative.
  2. Notation for the interfacial energy flux and the precise definition of the residual particle current should be introduced once in the bulk-equation section and used consistently thereafter.
  3. A brief remark on the range of validity (e.g., when the interface width remains negligible compared with the channel height) would clarify the domain of the macroscopic description.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for their positive summary and significance assessment of the manuscript, as well as the recommendation for minor revision. No specific major comments were raised in the report.

Circularity Check

0 steps flagged

No significant circularity identified

full rationale

The derivation applies standard Poiseuille flow and Fourier conduction in the bulk phases, closes with particle and energy conservation at the interface, and identifies that the resulting dimensionless groups A^L and A^G are O((micro/macro length)^2) ≪ 1 from the explicit length-scale separation. This structure directly yields pressure-drop localization and reduced current without any fitted parameters, self-citations, or self-definitional steps. The small-parameter argument is the expected macroscopic outcome of a molecular-scale interface and does not reduce the target claims to the inputs by construction. The paper is self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

2 free parameters · 2 axioms · 0 invented entities

The central claim rests on applicability of bulk Poiseuille and Fourier laws across macroscopic regions, conservation of particles and energy, and the emergence of A^L and A^G as small parameters from length-scale ratios.

free parameters (2)
  • A^L
    Dimensionless parameter for liquid region whose smallness originates from squared microscopic-to-macroscopic length ratios.
  • A^G
    Dimensionless parameter for gas region whose smallness originates from squared microscopic-to-macroscopic length ratios.
axioms (2)
  • domain assumption Poiseuille flow and Fourier heat conduction hold in the bulk liquid and gas regions
    Invoked to describe flow and heat transport away from the interface.
  • standard math Particle and energy conservation across the system
    Used to connect bulk regions and interface.

pith-pipeline@v0.9.1-grok · 5642 in / 1337 out tokens · 28558 ms · 2026-07-03T04:48:39.502612+00:00 · methodology

discussion (0)

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Reference graph

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