Toprakseven, ŞuayipDinibütün, Seza2025-07-252025-07-25202324736988https://hdl.handle.net/11494/5870We present a stabilizer-free weak Galerkin finite element method (SFWG-FEM) with polynomial reduction on a quasi-uniform mesh in space and Alikhanov’s higher order L2-1σ scheme for discretization of the Caputo fractional derivative in time on suitable graded meshes for solving time-fractional subdiffusion equations. Typical solutions of such problems have a singularity at the starting point since the integer-order temporal derivatives of the solution blow up at the initial point. Optimal error bounds in H1 norm and L2 norm are proven for the semi-discrete numerical scheme. Furthermore, we have obtained the values of user-chosen mesh grading constant r, which gives the optimal convergence rate in time for the fully discrete scheme. The optimal rate of convergence of order O(hk+1 + M−2) in the L∞ (L2)-norm has been established. We give several numerical examples to confirm the theory presented in this work.eninfo:eu-repo/semantics/openAccessGraded temporal meshesOptimal rate of convergenceStabilizer-free weak Galerkin finite element methodSub-diffusion problemsArticle812310223104910.3934/math.202315882-s2.0-85177218299Q1