ON UNIFORM SECOND-ORDER NONLOCAL APPROXIMATIONS TO DIFFUSION AND SUBDIFFUSION EQUATIONS WITH NONLOCAL EFFECT PARAMETER

作者：Yang, Jerry Z.; Yin, Xiaobo^*; Zhang, Jiwei

来源：Communications in Mathematical Sciences, 2022, 20(2): 359-375.

• Subdiffusion equation
• Caputo derivative
• maximum principle
• nonlocal model
• local limit
• asymptotically compatible

In this paper we focus on uniform convergence rates from nonlocal diffusion and subdiffusion solutions to the corresponding local limit with respect to a nonlocal effect parameter without extra assumptions on the regularity of nonlocal solutions, and present sufficient conditions to guarantee first- and second-order convergence rates, respectively. To do so, we first revisit the maximum principle for nonlocal models using the idea in [Luchko, J. Math. Anal. Appl., 2009], and present the uniqueness of the nonlocal solutions. After that, we extend the methodology developed in [Du, Zhang and Zheng, Commun. Math. Sci., 2019] to address the truncated errors on the volume constraints, and then combine the resulting errors from the boundary domain with the maximum principle to obtain the uniform convergence rates. Our analysis shows that the constant value continuation of the boundary conditions of local problems only leads to a first-order convergence rate. If one expects a second-order convergence rate, the information of first-order derivatives for local problems on the boundaries is required. One- and two-dimensional numerical examples are provided to validate our theoretical analysis.

• 单位
  武汉大学