Stretch narrows.
Diffusion spreads.
Set the strain and viscosity. Follow one Gaussian vortex as its core finds a balance—or keeps spreading.
Reduced motion is enabled. Choose still frames with the controls.
What this viewer reveals
Gaussian axial vorticity under fixed strain u_r=−ar/2, u_z=az. Initially w=8 mm; Γ=1000 mm²/s stays fixed. The contour marks 1/e of the peak.
q=w² · q′=4ν−aq
Substitution into the vorticity equation gives this width law. For a>0, steady radius is √(4ν/a). At a=0, q=64+4νt with no steady radius. Fixed dials: 0–20 mm and 0–350 s⁻¹.
The 24 mm window clips the infinite tail. Shading is relative to the current peak; brightness cannot compare absolute values between settings. The sample and circulation reading use this same field.
This cross-section uses imposed strain, whose velocity grows unboundedly at infinity. The infinite-energy family is outside Clay's finite-energy problem. Controls select trajectories from the same initial profile, without simulating a switched apparatus. No turbulence, instability, full3D solver or general regularity proof is supplied.
Gallay & Wayne: Burgers vortex and strain ↗
Gallay & Maekawa: the prescribed-strain model ↗
Ohkitani & Gibbon: infinite-energy geometry ↗