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| Nonlinear, irrotational
flow of Im(dz/z)
The magnetic field about an infinitely long straight wire carrying a constant current is irrotational, divergence free, but not constant. The integral curves are circles, but the nonlinear flow is completely different from the flow of the harmonic oscillator…… Annular regions are invariant, but the inside travels much faster than the outside, and needs to cover less distance.  |