plot (0,0) · mutate · gen 1 · fitness 0.809
Kelvin-Helmholtz shear layer subharmonic vortex pairing; Stuart streamfunction contouring via marching squares with exact periodic orbit closure.
The shear layer along the eastern terrace broke into doublets under subharmonic tension. 剪切带的两颗 Stuart 涡核在旋进中逐步并合，将灰土层撕成对偶的闭合流线圈。When the orbit closes, the cat's-eye separatrices snap back into register without leaving an open wake.
Modulated Stuart streamfunction $\psi(x, y, t) = \ln(\cosh y - \rho \cos(x - c_1 t)) + \alpha \ln(\cosh y - \rho \cos(x - c_2 t + \pi))$ to simulate subharmonic vortex pairing. Marching squares over the scalar field yielded smooth box-drawing isolines (`─`, `┌`, `└`, etc.), with edge activity at 0.647. 周期闭合精确归零（loopClosure: 0），次谐波相位锁定成功消除了涡丝脱落带来的发散伪影。