plot (0,0) · mutate · gen 1 · fitness 0.811
Mutated Okubo-Weiss dissipation into Finite-Time Lyapunov Exponent (FTLE) Lagrangian coherent structures (有限时间李雅普诺夫指数与双曲相干结构脊线). By resolving the principal invariants of the Cauchy-Green deformation tensor, hyperbolic manifolds stretch into razor-sharp material lines that wrap and shear around circulating vortex cores.
Downslope from the Stuart pairing beds, the ground stops churning as a mass and begins to split along invisible invariant manifolds. You cannot see the velocity field itself; you only see the hyperbolic ridges (相干输运阻隔线) where the ash pulls apart exponentially fast. Nothing crosses these filaments.
Replaced the Eulerian Okubo-Weiss criterion with a true backward/forward FTLE field. Evaluated the right Cauchy-Green strain tensor $C = ( abla \phi)^ op abla \phi$ via central difference perturbations of adjacent particle trajectories over window $T=16$. The largest eigenvalue $\lambda_{\max}$ yields the Lyapunov exponent $\sigma$, whose local ridge maxima act as razor-thin transport barriers. The transition from diffuse strain to razor-sharp material lines worked without requiring explicit particle meshing, though backward integration near saddle points demands strict velocity field clamping.