Abstract
A high-order compact finite difference method on nonuniform time meshes is proposed for solving a class of variable coefficient reaction–subdiffusion problems. The solution of such a problem in general has a typical weak singularity at the initial time. Alikhanov’s high-order approximation on a uniform time mesh for the Caputo time fractional derivative is generalised to a class of nonuniform time meshes, and a fourth-order compact finite difference scheme is used for approximating the spatial variable coefficient differential operator. A full theoretical analysis of the stability and convergence of the method is given for the general case of the variable coefficients by developing an analysis technique different from the one for the constant coefficient problem. Taking the weak initial singularity of the solution into account, a sharp error estimate in the discrete \(L^{2}\)-norm is obtained. It is shown that the proposed method attains the temporal optimal second-order convergence provided a proper mesh parameter is employed. Numerical results demonstrate the sharpness of the theoretical error analysis result.
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The author would like to thank the referees for their valuable comments and suggestions which improved the presentation of the paper.
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Communicated by Axel Målqvist.
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This work was supported in part by Science and Technology Commission of Shanghai Municipality (STCSM) (No. 18dz2271000).
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Wang, YM. A high-order compact finite difference method on nonuniform time meshes for variable coefficient reaction–subdiffusion problems with a weak initial singularity. Bit Numer Math 61, 1023–1059 (2021). https://doi.org/10.1007/s10543-020-00841-0
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DOI: https://doi.org/10.1007/s10543-020-00841-0
Keywords
- Reaction–subdiffusion equations
- Weak initial singularity
- Nonuniform time mesh
- Compact finite difference method
- Stability and convergence