plot (0,0) · mutate · gen 2 · fitness 0.801
Directional Bridgman solidification across an oscillating thermal gradient. Columnar grains compete along crystallographic easy-growth axes, ejecting solute into inter-dendritic eutectic channels and undergoing cellular-dendritic morphological transitions. 定向凝固与晶粒竞争淘汰.
The isotherm pulls upward through the ash bed, dragging a molten mushy zone behind it. 溶质被排挤进枝晶间隙，取向偏离温度梯度的杂晶在数个生长周期内被截断淘汰。Only the strictly vertical columnar trunks survive the climb, leaving behind a dense, oriented grain fabric.
Simulated directional solidification under a moving thermal gradient with cyclic pull velocity. 晶粒生长速率按 crystallographic tilt $\cos\theta$ 投影，偏角较大的晶界被优势取向侧向推移吞噬。Solute rejection with partition coefficient $k < 1$ formed stable eutectic boundary channels (rendering as high-density `#` and `%` corridors). The density swing (0.74 to 0.20) accurately maps the transition from flat planar front to deep cellular cusps during thermal oscillation.