Global $C^{1,α}$-Regularity for Musielak-Orlicz Equations in Divergence Form
Hlel Missaoui
TL;DR
This work extends elliptic regularity theory to divergence-form equations with Musielak–Orlicz growth, proving global $C^{1,\alpha}$-regularity for bounded generalized solutions of $-$div$ A(x,u,Du)=B(x,u,Du)$ under Dirichlet or Neumann conditions. The authors leverage Gehring-type higher integrability in Musielak–Orlicz spaces, compare with frozen-coefficient problems, and apply Campanato–Morrey estimates, together with boundary treatments, to obtain interior and boundary $C^{1,\alpha}$ regularity. The results generalize and unify variable-exponent, Orlicz, and double-phase growth frameworks, and they establish quantitative Hölder continuity of the gradient that depends on structural data and boundary smoothness. This provides a robust framework for nonstandard growth elliptic PDEs, including spatially dependent and highly nonuniform growth, with potential applications to heterogeneous media modeling.
Abstract
In this paper, we establish global $C^{1,α}$-regularity for bounded generalized solutions of elliptic equations in divergence form with Musielak-Orlicz growth and subject to Dirichlet or Neumann boundary conditions. In fact, our findings extend and generalize several important regularity results in cases of special attention such as variable exponent spaces, Orlicz spaces, and some $(p,q)$ situations. We also point out new conditions in the analysis that focus on the interplay between non-standard growth conditions and the boundary behavior in such generalized examples.
