Newly Developments in Fractional Laplacian: Numerical Methods and Inverse Problems

A special issue of Fractal and Fractional (ISSN 2504-3110). This special issue belongs to the section "General Mathematics, Analysis".

Deadline for manuscript submissions: closed (31 July 2023) | Viewed by 1913

Special Issue Editors


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Guest Editor
Department of Mathematics, Purdue University, West Lafayette, United States
Interests: scientific computing; numerical analysis; fractional calculus; stochastic differential equations

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Guest Editor
Department of mathematics, Southeast University, Nanjing 21189, China
Interests: numerical methods for fractional differential equations; lattice boltzmann method

Special Issue Information

Dear Colleagues,

During the past few decades, scientists have been exploring fractional calculus as a tool for developing more sophisticated but mathematically tractable models. The reason is that they can accurately describe complex physical phenomena, manifesting in long-range and nonlocal interactions, self-similar structures, sharp peaks, and memory effects. More and more people are accepting the fractional model as a promising remedy to the traditionally inaccurate integer-order model in many exciting applications. However, the efficient computation of this model on bounded domains is still challenging as highly accurate and efficient numerical methods are not yet available, which prevents its broader applications among the scientific and engineering community. This Special Issue will focus on recent developments in numerical methods.

Moreover, regularity plays a crucial role in developing numerical methods. As limited regularity results exist, this issue also welcomes the submission of PDE theory involving the new regularity results. Another exciting topic this Special Issue will focus on is extending the neural networks to inverse fractional problems on model learning via optimal control and machine learning techniques. Fractional models for materials and media are often hand-tuned or rely on engineering or scientific intuition. When limited data or a priori information are available, one can resort to solving an inverse problem to recover the unknown parameters and define a more accurate, data-driven mathematical model.

Dr. Zhao-peng Hao
Dr. Rui Du
Guest Editors

Manuscript Submission Information

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Keywords

  • Fractional Laplacian 
  • Regularity 
  • Numerical methods 
  • Inverse problem 
  • Machine learning

Published Papers (2 papers)

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Research

17 pages, 1066 KiB  
Article
A Monotone Discretization for the Fractional Obstacle Problem and Its Improved Policy Iteration
by Rubing Han, Shuonan Wu and Hao Zhou
Fractal Fract. 2023, 7(8), 634; https://doi.org/10.3390/fractalfract7080634 - 20 Aug 2023
Viewed by 688
Abstract
In recent years, the fractional Laplacian has attracted the attention of many researchers, the corresponding fractional obstacle problems have been widely applied in mathematical finance, particle systems, and elastic theory. Furthermore, the monotonicity of the numerical scheme is beneficial for numerical stability. The [...] Read more.
In recent years, the fractional Laplacian has attracted the attention of many researchers, the corresponding fractional obstacle problems have been widely applied in mathematical finance, particle systems, and elastic theory. Furthermore, the monotonicity of the numerical scheme is beneficial for numerical stability. The purpose of this work is to introduce a monotone discretization method for addressing obstacle problems involving the integral fractional Laplacian with homogeneous Dirichlet boundary conditions over bounded Lipschitz domains. Through successful monotone discretization of the fractional Laplacian, the monotonicity is preserved for the fractional obstacle problem and the uniform boundedness, existence, and uniqueness of the numerical solutions of the fractional obstacle problems are proved. A policy iteration is adopted to solve the discrete nonlinear problems, and the convergence after finite iterations can be proved through the monotonicity of the scheme. Our improved policy iteration, adapted to solution regularity, demonstrates superior performance by modifying discretization across different regions. Numerical examples underscore the efficacy of the proposed method. Full article
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16 pages, 374 KiB  
Article
Globally Existing Solutions to the Problem of Dirichlet for the Fractional 3D Poisson Equation
by Toshko Boev and Georgi Georgiev
Fractal Fract. 2023, 7(2), 180; https://doi.org/10.3390/fractalfract7020180 - 11 Feb 2023
Viewed by 854
Abstract
A general approach to solving the Dirichlet problem, both for bounded 3D domains and for their unbounded complements, in terms of the fractional (3D) Poisson equation, is presented. Lauren Schwartz class solutions are sought for tempered distributions. The solutions [...] Read more.
A general approach to solving the Dirichlet problem, both for bounded 3D domains and for their unbounded complements, in terms of the fractional (3D) Poisson equation, is presented. Lauren Schwartz class solutions are sought for tempered distributions. The solutions found are represented by a formula that contains the volume Riesz potential and the one-layer potential, the latter depending on the boundary data. Infinite regularity of fractional harmonic functions, analogous to the infinite smoothness of the classical harmonic functions, is also proved in the respective domain, no matter what the boundary conditions are. Other properties of the solutions, that are presumably of interest to mathematical physics, are also investigated. In particular, an intrinsic decay property, valid far from the common boundary, is shown. Full article
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