# Sharp interface limit of a non-mass-conserving Cahn--Hilliard system with source terms and non-solenoidal Darcy flow

## TL;DR

This paper investigates the sharp interface limit of a non-mass-conserving Cahn--Hilliard--Darcy system with source terms, addressing new mathematical challenges and establishing results under specific structural conditions.

## Contribution

It introduces a novel analysis of the sharp interface limit for a non-mass-conserving Cahn--Hilliard--Darcy system with source terms, extending previous methods to non-solenoidal flows.

## Key findings

- Established uniform estimates despite source terms
- Derived local-in-time sharp interface limit results
- Discussed extension to Cahn--Hilliard--Brinkman system

## Abstract

We study the sharp interface limit of a non-mass-conserving Cahn--Hilliard--Darcy system with the weak compactness method developed in Chen (J. Differential Geometry, 1996). The source term present in the Cahn--Hilliard component is a product of the order parameter and a prescribed function with zero spatial mean, leading to non-conservation of mass. Furthermore, the divergence of the velocity field is given by another prescribed function with zero spatial mean, which yields a coupling of the Cahn--Hilliard equation to a non-solenoidal Darcy flow. New difficulties arise in the derivation of uniform estimates due to the presence of the source terms, which can be circumvented if we consider the above specific structures. Moreover, due to the lack of mass-conservation, the analysis is valid as long as one phase does not vanish completely, leading to a local-in-time result. The sharp interface limit for a Cahn--Hilliard--Brinkman system is also discussed.