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We consider the multidimensional space-fractional diffusion equations with spatially varying diffusivity and fractional order. Significant computational challenges are encountered when solving these equations due both to the kernel…

Numerical Analysis · Mathematics 2021-08-31 Hasnaa Alzahrani , George Turkiyyah , Omar Knio , David Keyes

We discuss the derivation and the solutions of integro-differential equations (variable-order time-fractional diffusion equations) following as continuous limits for lattice continuous time random walk schemes with power-law waiting-time…

Statistical Mechanics · Physics 2020-07-22 Philipp Roth , Igor M. Sokolov

We develop a sparse spectral method for a class of fractional differential equations, posed on $\mathbb{R}$, in one dimension. These equations can include sqrt-Laplacian, Hilbert, derivative and identity terms. The numerical method utilizes…

Numerical Analysis · Mathematics 2024-06-12 Ioannis P. A. Papadopoulos , Sheehan Olver

In the paper we deal with linear fractional control problems with constant delays in the state. Single-order systems with fractional derivative in Caputo sense of orders between 0 and 1 are considered. The aim is to introduce a new…

Numerical Analysis · Mathematics 2024-12-20 Josef Rebenda , Zdeněk Šmarda

This paper is devoted to an in deep investigation of the first fundamental solution to the linear multi-dimensional space-time-fractional diffusion-wave equation. This equation is obtained from the diffusion equation by replacing the first…

Analysis of PDEs · Mathematics 2021-03-12 Yuri Luchko

Semi-Lagrangian methods have traditionally been developed in the framework of hyperbolic equations, but several extensions of the Semi-Lagrangian approach to diffusion and advection--diffusion problems have been proposed recently. These…

Numerical Analysis · Mathematics 2014-05-20 L. Bonaventura , R. Ferretti

This paper is devoted to describing a linear diffusion problem involving fractional-in-time derivatives and self-adjoint integro-differential space operators posed in bounded domains. One main concern of our paper is to deal with singular…

Analysis of PDEs · Mathematics 2023-04-11 Hardy Chan , Juan Luis Vázquez , David Gómez-Castro

This work explores different particle-based approaches to the simulation of one-dimensional fractional subdiffusion equations in unbounded domains. We rely on smooth particle approximations, and consider four methods for estimating the…

Numerical Analysis · Mathematics 2017-07-14 S. Allouch , M. Lucchesi , O. P. Le Maître , K. A. Mustapha , O. M. Knio

In this paper, we develop and analyze a stochastic algorithm for solving space-time fractional diffusion models, which are widely used to describe anomalous diffusion dynamics. These models pose substantial numerical challenges due to the…

Numerical Analysis · Mathematics 2025-08-29 Tengteng Cui , Chengtao Sheng , Bihao Su , Zhi Zhou

This paper is concerned with the fractional evolution equation with a discrete distribution of Caputo time-derivatives such that the largest and the smallest orders, $\alpha$ and $\alpha_m$, satisfy the conditions $1<\alpha\le 2$ and…

Analysis of PDEs · Mathematics 2018-01-11 Emilia Bazhlekova , Ivan Bazhlekov

In this paper we want to propose practical numerical methods to solve a class of initial-boundary problem of time-space fractional convection-diffusion equations (TSFCDEs). To start with, an implicit difference method based on two-sided…

Numerical Analysis · Mathematics 2021-07-26 Xian-Ming Gu , Ting-Zhu Huang , Cui-Cui Ji , Bruno Carpentieri , Anatoly A. Alikhanov

The focus of this paper is on the concurrent reconstruction of both the diffusion and potential coefficients present in an elliptic/parabolic equation, utilizing two internal measurements of the solutions. A decoupled algorithm is…

Numerical Analysis · Mathematics 2023-08-08 Siyu Cen , Zhi Zhou

In this article, we consider the following stochastic fractional diffusion equation \begin{equation*} \left(\partial^{\beta}+\dfrac{\nu}{2}\left(-\Delta\right)^{\alpha / 2}\right) u(t, x)= \lambda\: I_{0_+}^{\gamma}\left[u(t, x) \dot{W}(t,…

Probability · Mathematics 2023-03-22 Yuhui Guo , Jian Song , Xiaoming Song

In this work, we explore a time-fractional diffusion equation of order $\alpha \in (0,1)$ with a stochastic diffusivity parameter. We focus on efficient estimation of the expected values (considered as an infinite dimensional integral on…

Numerical Analysis · Mathematics 2024-09-04 Josef Dick , Hecong Gao , William McLean , Kassem Mustapha

In this paper, we investigate fast algorithms in the small fraction order regime to approximate the Caputo derivative $^C_0D_t^\alpha u(t)$ when $\alpha$ is small. We focus on two fast algorithms, i.e. FIR and FIDR, both relying on the…

Numerical Analysis · Mathematics 2021-10-22 Zihang Zhang , Qiwei Zhan , Zhennan Zhou

We develop a high-order, explicit method for acoustic scattering in three space dimensions based on a combined-field time-domain integral equation. The spatial discretization, of Nystr\"om type, uses Gaussian quadrature on panels combined…

Numerical Analysis · Mathematics 2020-01-29 Alex H. Barnett , Leslie Greengard , Tom Hagstrom

This paper deals with the investigation of the computational solutions of an unified fractional reaction-diffusion equation, which is obtained from the standard diffusion equation by replacing the time derivative of first order by the…

Analysis of PDEs · Mathematics 2012-10-05 R. K. Saxena , A. M. Mathai , H. J. Haubold

In this article, we have studied the convergence behavior of the Dirichlet-Neumann and Neumann- Neumann waveform relaxation algorithms for time-fractional sub-diffusion and diffusion-wave equations in 1D & 2D for regular domains, where the…

Numerical Analysis · Mathematics 2022-12-26 Soura Sana , Bankim C. Mandal

In this work, we investigate the recovery of a parameter in a diffusion process given by the order of derivation in time for a class of diffusion type equations, including both classical and time-fractional diffusion equations, from the…

Analysis of PDEs · Mathematics 2021-11-04 Bangti Jin , Yavar Kian

We analyze upwind difference methods for strongly degenerate convection-diffusion equations in several spatial dimensions. We prove that the local $L^1$-error between the exact and numerical solutions is $\mathcal{O}(\Delta x^{2/(19+d)})$,…

Analysis of PDEs · Mathematics 2015-09-07 Kenneth Hvistendahl Karlsen , Nils Henrik Risebro , Erlend Briseid Storrøsten