A Hele-Shaw problem with interior and free boundary oscillation: well-posedness and homogenization

TL;DR

This paper studies a one-dimensional Hele-Shaw free boundary problem with interior and boundary heterogeneities, establishing well-posedness via viscosity flows and proving stochastic homogenization under ergodic assumptions, with novel approximation techniques.

Contribution

It introduces a new notion of viscosity flows for well-posedness and proves stochastic homogenization for a complex free boundary problem with interior heterogeneities.

Findings

Established well-posedness and comparison principle.

Proved stochastic homogenization under ergodic coefficients.

Developed a new approximation method for effective free boundary velocity.

Abstract

We investigate a Hele-Shaw type free boundary problem in one spatial dimension, where heterogeneities appear both on the free boundary and within the interior of the positivity set. Our contributions are twofold. First, we establish well-posedness and a comparison principle for the problem by introducing a novel notion of viscosity flows. Second, under the assumption that the coefficients are stationary ergodic, we prove a stochastic homogenization result. Our results are new even in the periodic setting. To derive the effective free boundary velocity, we use a new approximation that accounts for both interior homogenization and free boundary propagation.