We present a geometric framework for studying the regularity problem of the 3D Navier–Stokes equations. The central object is the vorticity anisotropy A(ω) ∈0,1, measuring how strongly one component of the vorticity dominates the others. The flow domain is partitioned into three zones according to A, and we show that the Caffarelli–Kohn–Nirenberg singular set is empty in each zone by different mechanisms. The key observation is that incompressibility alone (tr S = 0) suppresses vortex stretching in the isotropic zone, yielding a parabolic inequality without source term. Viscosity controls the boundary zone, and a quasi-1D structure governs the deep anisotropic zone.
Zhanat Alimkhojayeva (Sat,) studied this question.
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