Tip-splitting instability in directional solidification based on bias field method
You Jia-Xue, Wang Zhi-Jun, Li Jun-Jie, Wang Jin-Cheng†
       
Schematics of cellular tip splitting. Influence of a zero in the time rate of change of freezing at location φ *; where the surface Laplacians of the potential, or curvature, vanish, i.e., Ф n = 0.