Curvature-Driven Interface Motion

Allen-Cahn equation — mean curvature flow, shrinking droplets

Parameters

Interface area
Largest droplet R
Step0
Phase +1 fraction
Allen-Cahn equation:
∂_t φ = M(ε²∇²φ − W'(φ))
W(φ)=¼(φ²−1)², W'=φ(φ²−1)
Interface moves with normal velocity v_n=M·κ (mean curvature).
Circular droplet radius: R(t)=√(R₀²−2Mt).
Onsager variational principle: minimizes free energy.