Inviscid 2D fluid — vortex point interactions and Kelvin's theorem
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Physics
The Euler equations describe inviscid incompressible flow: ∂ω/∂t + (u·∇)ω = 0. In 2D, vorticity ω is conserved along streamlines (Kelvin's theorem). Point vortices interact via the Biot-Savart law: u = Γ/(2π) × r⊥/r². Like-sign vortices orbit each other; opposite-sign pairs translate together. Pairs with equal and opposite circulation form a dipole that travels in a straight line. Click the canvas to add vortices.