Up to the Boundary Gradient Estimates for Nonlinear PDEs and Applications in Free Boundary Problems
摘要
In this paper, we establish sharp up-to-the-boundary gradient estimates for weak solutions of the Dirichlet problem involving nonlinear partial differential equations (PDEs) with non-standard growth conditions and unbounded source terms. Solutions are analyzed within a suitable Orlicz–Sobolev framework. Leveraging these estimates, we derive optimal boundary gradient bounds for a class of free boundary problems, and subsequently prove Lipschitz regularity for a flame propagation model. Our results extend those available in the literature and allow for the treatment of applications in mathematical physics under even more challenging scenarios.