Sharp interface limit in a phase field model of cell motility

TL;DR

This paper analyzes the sharp interface limit of a phase field model for cell motility, deriving interface motion equations, rigorously justifying the limit in 1D, and exploring stability, discontinuities, and traveling waves through analysis and simulations.

Contribution

It formally derives the interface motion equation, rigorously justifies the sharp interface limit in 1D, and investigates stability and wave phenomena in the model.

Findings

Derived an interface motion equation with mean curvature and nonlinear terms.

Proved the sharp interface limit rigorously in 1D.

Discovered velocity discontinuities and hysteresis phenomena through simulations.

Abstract

We consider a system of two coupled parabolic PDEs introduced in [1] to model motility of eukaryotic cells. We study the asymptotic behavior of solutions in the limit of a small parameter related to the width of the interface in phase field function (sharp interface limit). We formally derive an equation of motion of the interface, which is mean curvature motion with an additional nonlinear term. In a 1D model parabolic problem we rigorously justify the sharp interface limit. To this end, a special form of asymptotic expansion is introduced to reduce analysis to a single nonlinear PDE. Further stability analysis reveals a qualitative change in the behavior of the system for small and large values of the coupling parameter. Using numerical simulations we also show discontinuities of the interface velocity and hysteresis. Also, in the 1D case we establish nontrivial traveling waves when the coupling parameter is large enough.