Variable-order space-fractional diffusion equations and a variable-order modification of constant-order fractional problems. Issue 6 (13th April 2022)

• Record Type: Journal Article
• Authors: Zheng, Xiangcheng; Wang, Hong
• Is Part Of: Applicable analysis. Volume 101:Issue 6(2022)
• Page Start: 1848
• Page End: 1870
• Publication Date: 2022-04-13
• Subjects: Variable-order space-fractional diffusion equation -- variable-order modification of constant-order problem -- two-sided -- wellposedness -- regularity; 35J40 -- 35A01 -- 35A02 -- 35A20; Mathematical analysis -- Periodicals; 515
• DOI: 10.1080/00036811.2020.1789596
• Languages: English
• ISSNs: 0003-6811

Abstract

ABSTRACT: Fractional diffusion equations (FDEs) were shown to provide very competitive descriptions of challenging phenomena of anomalously diffusive transport or long-range interactions. However, FDEs introduce mathematical issues that are not common in the context of integer-order diffusion equations. For instance, the homogeneous Dirichlet boundary-value problems of linear elliptic FDEs with smooth data in one space dimension may generate solutions with singularities that do not seem physically relevant, which are in sharp contrast to their integer-order analogues do. We prove the wellposedness of the Dirichlet boundary-value problem of one dimensional variable-order linear space-fractional diffusion equations (sFDEs). We further prove that their solutions have the similar regularities as their integer-order analogues if the order has an integer limit at the boundary or have the same singularity near the boundary as their constant-order sFDE analogues if the order has a non-integer limit at the boundary. In particular, we prove that constant-order sFDEs with a variable-order modification indeed generate solutions with significantly improved regularities.