Special Session 167: Functional spaces and multiphase problems

A new class of anisotropic double phase problems: exponents depending on solutions and their gradients
Anouar Bahrouni
University of Monastir
Tunisia
Co-Author(s):    Ala Eddine Bahrouni and Hlel Missaoui
Abstract:
In this talk, we deal with two novel classes of quasilinear elliptic equations, each driven by the double phase operator with variable exponents. The first class features a new double phase equation where exponents depend on the gradient of the solution. We delve into giving various properties of the corresponding Musielak-Orlicz Sobolev spaces, including the $\Delta_2$ property, uniform convexity, density and compact embedding. Additionally, we explore the characteristics of the new double phase operator, such as continuity, strict monotonicity, and the (S$_+$)-property. Employing both variational and nonvariational methods, we deal with the existence of solutions for this inaugural class of double phase equations. In the second category, the treatment of exponents is dependent on the solution itself. This class differs from the first one due to the unavailability of suitable Musielak-Orlicz Sobolev spaces. For this reason, we employ a perturbation argument that leads to the classical double phase class. These two new classes highlight how different physical processes like the movement of special fluids through porous materials, phase changes, and fluid dynamics interact with each other.