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Preprint . 2026
License: CC BY
Data sources: Datacite
ZENODO
Preprint . 2026
License: CC BY
Data sources: Datacite
ZENODO
Preprint . 2026
License: CC BY
Data sources: Datacite
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Quadrupole-Depletion Route to $L^3$ Regularity for 3D Incompressible Navier--Stokes

Authors: Thomson, David;

Quadrupole-Depletion Route to $L^3$ Regularity for 3D Incompressible Navier--Stokes

Abstract

Version v1.1 (technical clarification and citation-tightening). This release corrects and clarifies the localized tail accounting in the entropy-pressure localization, and it tightens the harmonic-analysis citations at the exact points where Calderon--Zygmund commutator machinery is invoked. The main quadrupole-depletion mechanism (the $\ell=2$ angular derivative gain and the reduction to a single depletion functional) is unchanged; v1.1 improves rigor and traceability of the localized estimates used in the closure routes. Tail term in the localized entropy-pressure bound is made explicit. In the localized entropy-pressure lemma, the previously schematic phrase that the tail term is "any sum of far-field and cutoff debris" is replaced by a concrete estimate controlled directly by the Tail Lemma. For every $\theta\in(0,1)$ there exists a universal constant $C_\theta0\}$ (interpreted as $0$ on $\{|v|=0\}$ in mollified limits), $\mathcal{B}_{\phi,r_0}$ is the explicit local budget appearing in the paper, and $\Lambda(\rho)$ is defined below. This removes ambiguity in how far-field and cutoff-commutator pieces are absorbed into the localized entropy inequality. Far-field kernel accounting corrected (outer-scale logarithm). The far-field contribution of the degree $-3$ Calderon--Zygmund kernel over the annulus $\rho\lesssim |z|\lesssim L$ generates a dyadic shell sum with radial weight $dr/r$, hence an explicit outer-scale factor\[\Lambda(\rho):=1+\log\!\Big(\frac{L}{\rho}\Big),\]where $L$ is the chosen outer reference scale (e.g. the maximal localization scale used in the depletion functional, or the torus diameter in the periodic setting). This factor is now stated and tracked explicitly in the Tail Lemma and in localized bounds that depend on the far-field annulus. Commutator-theory citations placed at the relevant proof steps. References to standard Calderon--Zygmund kernel representations and commutator estimates are inserted precisely where the principal value kernel form of the commutator and the commutator-to-square-function reduction are invoked (Stein; Grafakos; Coifman--Rochberg--Weiss), aligning the manuscript with classical harmonic-analysis sources for these steps. Summary. Version v1.1 is a technical update: it (i) makes the localized tail term quantitatively explicit inside the entropy-pressure lemma, (ii) corrects far-field scale summation by introducing the explicit factor $\Lambda(\rho)=1+\log(L/\rho)$ where appropriate, and (iii) tightens citations for the Calderon--Zygmund/commutator machinery used in the commutator route. No structural changes are made to the quadrupole-depletion framework or to the definition and role of the scale-invariant depletion functional.

This upload contains a self-contained research manuscript proposing a single, unified proof program for global regularity of the three-dimensional incompressible Navier--Stokes equations, organized around the critical $L^3$ dissipation identity and an explicit algebraic cancellation in the pressure Hessian. We consider the incompressible Navier--Stokes system (on $\mathbb{T}^3$ or $\mathbb{R}^3$ with decay)\[\partial_t v + (v\cdot\nabla)v = -\nabla p + \nu \Delta v,\qquad \nabla\cdot v = 0,\]with viscosity $\nu>0$. The pressure is determined by\[-\Delta p = \partial_j\partial_k(v_j v_k),\qquadp = \mathcal{R}_j\mathcal{R}_k(v_j v_k),\]where $\mathcal{R}_j$ are Riesz transforms. The starting point is the critical $L^3$ identity\[\frac{d}{dt}\|v(t)\|_3^3 + 3\nu D_3(v(t)) = -3\int |v|\, v\cdot\nabla p\,dx,\]with\[D_3(v) := \int\left(|v|\,|\nabla v|^2 + \frac{(v\cdot\nabla v)^2}{|v|}\right)\,dx.\]Global regularity follows if the pressure work satisfies\[\left|\int |v|\, v\cdot\nabla p\,dx\right| \le c\,D_3(v)\quad\text{for some } c0\}\text{)}.\]A localized entropy identity is derived by testing the local speed equation against a cutoff weight and $\log(u/r_0)$, which produces the coercive term $\nu\int q$ exactly. A tube/ball packing mechanism is then proposed to convert largeness of $\Theta$ at a scale into a quantitative dissipation payment on that scale (up to a slow logarithmic factor related to the viscous core scale). (B) Coherent tubes imply depletion.Under a coherent-tube regime (vorticity-direction coherence plus a circulation lower bound of the form $u \gtrsim \rho|\omega|$ on high-vorticity sets), one obtains a Carleson/Morrey bound that forces $\Theta(v)$ to be small, giving an explicit conditional global regularity theorem with a falsifiable scale-selection rule for the threshold parameter. The manuscript concludes with three concrete remaining tasks for an unconditional proof:(i) a fully detailed localized quadrupole-commutator estimate (with tail control suitable for scale extraction);(ii) elimination of the remaining slow logarithm in the packing route via a scale-invariant gate in hypothetical blow-up regimes;(iii) a rigidity alternative showing that any attempt for $\Theta$ to cross the threshold forces dissipation incompatible with global $L^3$ / energy budgets.

Keywords

pressure commutator, Riesz transforms, Navier--Stokes, speed entropy, scale-invariant depletion, Millennium problem, Morrey bound, tube packing, Carleson measure, localized entropy, quadrupole cancellation, vorticity coherence, L3 criterion

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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
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