A variable diffusivity fractional Laplacian

Abstract

In this paper we analyze the existence, uniqueness and regularity of the solution to the generalized, variable diffusivity, fractional Laplace equation on the unit disk in ${\mathbb{R}}^2$. For $\alpha$ the order of the differential operator, our results show that for the symmetric, positive definite, diffusivity matrix, $K(\mathbf{x})$, satisfying ${\lambda }_m{\mathbf{v}}^T\mathbf{v}\le {\mathbf{v}}^{T}K(\mathbf{x})\mathbf{v}\le {\lambda }_M{\mathbf{v}}^T\mathbf{v}$, for all $\mathbf{v}\in {\mathbb{R}}^2$, $\mathbf{x}\in \Omega$, with ${\lambda }_M<\frac{\sqrt{\alpha (2+\alpha )}}{(2-\alpha )}{\lambda }_m$, the problem has a unique solution. The regularity of the solution is given in an appropriately weighted Sobolev space in terms of the regularity of the right hand side function and $K(\mathbf{x})$.