Motion of discrete interfaces through mushy layers

TL;DR

This paper investigates the geometric evolution of discrete interfaces in ferromagnetic materials with weak inclusions, revealing a complex motion influenced by mushy layers that affects convergence and resembles phenomena in binary melt cooling.

Contribution

It introduces a model capturing the motion of the 'bulky' part of the interface influenced by mushy layers, showing weak convergence and non-commuting energy and evolution limits.

Findings

Bulky part follows motion by crystalline mean curvature with forcing.

Mushy layers cause weak convergence of discrete motions.

Phenomena resemble cooling processes in binary melts.

Abstract

We study the geometric motion of sets in the plane derived from the homogenization of discrete ferromagnetic energies with weak inclusions. We show that the discrete sets are composed by a `bulky' part and an external `mushy region' composed only of weak inclusions. The relevant motion is that of the bulky part, which asymptotically obeys to a motion by crystalline mean curvature with a forcing term, due to the energetic contribution of the mushy layers, and pinning effects, due to discreteness. From an analytical standpoint it is interesting to note that the presence of the mushy layers imply only a weak and not strong convergence of the discrete motions, so that the convergence of the energies does not commute with the evolution. From a mechanical standpoint it is interesting to note the geometrical similarity of some phenomena in the cooling of binary melts.