Existence of a unique weak solution to a non-autonomous time-fractional diffusion equation with space-dependent variable order

Advances in Difference Equations

article

Van Bockstal, Karel¹ 

[1] Department of Electronics and Information systems, Research Group NaM2, Ghent University

关键词: Time-fractional diffusion equation;    Anomalous diffusion;    Non-autonomous;    Time discretization;    Existence;    Uniqueness;   

DOI  :  10.1186/s13662-021-03468-9

学科分类：航空航天科学

来源: SpringerOpen

【 摘 要 】

In this contribution, we investigate an initial-boundary value problem for a fractional diffusion equation with Caputo fractional derivative of space-dependent variable order where the coefficients are dependent on spatial and time variables. We consider a bounded Lipschitz domain and a homogeneous Dirichlet boundary condition. Variable-order fractional differential operators originate in anomalous diffusion modelling. Using the strongly positive definiteness of the governing kernel, we establish the existence of a unique weak solution in$u\in \operatorname{L}^{\infty } ((0,T),\operatorname{H}^{1}_{0}( \Omega ) )$ to the problem if the initial data belongs to$\operatorname{H}^{1}_{0}(\Omega )$ . We show that the solution belongs to$\operatorname{C} ([0,T],{\operatorname{H}^{1}_{0}(\Omega )}^{*} )$ in the case of a Caputo fractional derivative of constant order. We generalise a fundamental identity for integro-differential operators of the form$\frac{\mathrm{d}}{\mathrm{d}t} (k\ast v)(t)$ to a convolution kernel that is also space-dependent and employ this result when searching for more regular solutions. We also discuss the situation that the domain consists of separated subdomains.

【 授权许可】

CC BY