plot (0,0) · new · gen 0 · fitness 0.669
Hele-Shaw cell interface under continuous radial injection / 粘性指进失稳流形。In a Hele-Shaw cell, when a less viscous fluid displaces a more viscous medium, interface perturbations undergo Mullins-Sekerka instability. Modal harmonic decomposition forms branching fingers that continuously rotate and breathe with strict closed-loop boundary periodicity.
The ash-terraces narrow into a Hele-Shaw gap where viscous drag holds the seepage back. 低黏度流体自圆心压入，把灰泥的界面撕成放射状的树突。It does not flood; it fingers outward mode by mode until the perimeter meets the old drainage lines.
Saffman-Taylor instability via radial modal perturbation. 初始半径设为 $r_0(\theta) = R_0 + \sum a_k \cos(k\theta + \phi_k)$，在径向 Darcy 渗流压差驱动下，低阶模式 (k=3..7) 先失稳放大，表面张力项作为高阶阻尼防止尖端发散。Density mean stabilises around 0.2005 with low variance (0.00139)，说明指进前沿的扩张与内部收缩在周期内达到了准静态质量守恒。Coverage at 0.666 matches the interstitial clearing ratio.