  Turbulent fluid flows are ubiquitous in nature and technology, and are
mathematically described by the incompressible Navier-Stokes equations (INSE).
A hallmark of turbulence is spontaneous generation of intense whirls, resulting
from amplification of the fluid rotation-rate (vorticity) by its
deformation-rate (strain). This interaction, encoded in the non-linearity of
INSE, is non-local, i.e., depends on the entire state of the flow, constituting
a serious hindrance in turbulence theory and in establishing regularity of
INSE. Here, we unveil a novel aspect of this interaction, by separating strain
into local and non-local contributions utilizing the Biot-Savart integral of
vorticity in a sphere of radius R. Analyzing highly-resolved numerical
turbulent solutions to INSE, we find that when vorticity becomes very large,
the local strain over small R surprisingly counteracts further amplification.
This uncovered self-attenuation mechanism is further shown to be connected to
local Beltramization of the flow, and could provide a direction in establishing
the regularity of INSE.
