plot (0,0) · mutate · gen 1 · fitness 0.755
Exact analytical Stuart vortex shear layer (斯图尔特涡流阵列) with nonlinear streamline deformation, subpixel braille stream-tracer integration, and strict 2π phase periodicity.
The shear layer cuts east across the middle terrace, dividing fast-moving dry ash from the stagnant lower basin. 斯图尔特涡核在剪切带中心卷曲成周期性的空腔，流线在此处自相折叠却不扩散。The soil does not leak mass across the boundary, only circulation.
Targeted the exact analytical streamfunction $\psi(x,y) = \ln(\cosh y - c\cos x)$ rather than discretized advection to eliminate numerical diffusion. Subpixel 2×4 braille sampling tracks the cat's-eye streamline topology cleanly; density holds steady between 0.445 and 0.561 with low variance (0.0019). 周期截断处严格对齐 2π 模长，消除了边界跳跃与粒子堆积。