Gas Centrifuge Radial Separation: Langevin Cross-Section

This is the 2D companion to the 3D gas-centrifuge simulator, and it reaches the same isotope-separation physics by a genuinely different, independently-computed route. Instead of animating molecules toward an authored bias band, it integrates the actual overdamped Langevin equation that governs a UF₆ molecule's radial position in the rotor's rotating frame — including the polar-coordinate entropic term a correct 2D reduction requires — using the exact closed-form update for the underlying stochastic differential equation every substep. Watch the top-down rotor cross-section fill with light and heavy molecules under their own simulated Brownian dynamics, then compare the separation factor measured live off a log-density regression of the resulting ensemble against the closed-form barometric-law prediction the 3D scene uses. A standalone Node verification of the same algorithm confirms the measured separation factor tracks the analytic prediction to within normal statistical noise for a population this size.