Youth Review
Zhang Jiwei
As the nonlocal model can describe the singularity and discontinuity mechanism of some important physical phenomena, it has been widely used in many fields in recent years and has played a strong role in promoting the development of related disciplines. As an important nonlocal model, anomalous diffusion model is used to describe anomalous diffusion phenomena. The nonlocality and multi-scale characteristics of nonlocal models not only promote the discovery of new mathematical theories, but also provide a new perspective for the existing discrete and local continuous models and their connections. Although there have been many achievements, there is a broad space for the development of multi-scale nonlocal and anomalous diffusion models, whether from the perspective of mathematical methods, basic theories or numerical methods. It is a research focus to further develop and improve the basic mathematical theories and methods, and develop new efficient numerical schemes under the condition of real solution regularity, especially the numerical schemes with stability, convergence and asymptotic compatibility. In the past few years, the author of this paper has been committed to the research of mathematical theory and numerical methods of nonlocal models, and has made some meaningful research results in the design of artificial boundary conditions, nonlocal maximum principle and asymptotically compatible numerical schemes. In the numerical analysis of anomalous diffusion equations, the fast algorithm of Caputo derivative and the discrete fractional Grönwall inequality are developed, and the idea of error convolution structure is proposed to represent the local consistent error, which provides some basic analysis frameworks for the optimal error estimation of a class of widely-used variable-step-size numerical schemes. There is still a long way to completely solve various mathematical problems in nonlocal and anomalous diffusion models, which needs further study. It is hoped that this paper can play a role in promoting the in-depth development of basic theories and algorithms of multi-scale nonlocal and anomalous diffusion models.