Linking discrete and continuum diffusion models: Well-posedness and stable finite element discretizations

TL;DR

This paper investigates the mathematical integration of continuum and discrete diffusion models, establishing well-posedness and stable finite element discretizations, with numerical validation and applications to incomplete data scenarios.

Contribution

It introduces a novel framework for linking different diffusive models, proving stability and convergence, and demonstrating practical applications.

Findings

Unconditional stability of linked models for stationary problems

Convergence of finite element discretizations with mixed elements

Numerical examples illustrating model linking effects

Abstract

In the context of mathematical modeling, it is sometimes convenient to integrate models of different nature. These types of combinations, however, might entail difficulties even when individual models are well-understood, particularly in relation to the well-posedness of the ensemble. In this article, we focus on combining two classes of dissimilar diffusive models: the first one defined over a continuum and the second one based on discrete equations that connect average values of the solution over disjoint subdomains. For stationary problems, we show unconditional stability of the linked problems and then the stability and convergence of its discretized counterpart when mixed finite elements are used to approximate the model on the continuum. The theoretical results are highlighted with numerical examples illustrating the effects of linking diffusive models. As a side result, we show that the methods introduced in this article can be used to infer the solution of diffusive problems with incomplete data.