Error estimations of a weak Galerkin finite element method for a linear system of ℓ ≥ 2 coupled singularly perturbed reaction-diffusion equations in the energy and balanced norms

Toprakseven Ş., Dinibutun S.

AIMS Mathematics, cilt.8, sa.7, ss.15427-15465, 2023 (SCI-Expanded, Scopus) identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 8 Sayı: 7
  • Basım Tarihi: 2023
  • Doi Numarası: 10.3934/math.2023788
  • Dergi Adı: AIMS Mathematics
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Directory of Open Access Journals
  • Sayfa Sayıları: ss.15427-15465
  • Anahtar Kelimeler: boundary layers, discrete gradient operator, energy and balanced norm, linear system of singularly reaction-diffusion problems, weak Galerkin finite element method
  • Yozgat Bozok Üniversitesi Adresli: Evet

Özet

This paper introduces a weak Galerkin finite element method for a system of ℓ ≥ 2 coupled singularly perturbed reaction-diffusion problems. The proposed method is independent of parameter and uses piecewise discontinuous polynomials on interior of each element and constant on the boundary of each element. By the Schur complement technique, the interior unknowns can be locally efficiently eliminated from the resulting linear system, and the degrees of freedom of the proposed method are comparable with the classical FEM. It has been reported that the energy norm is not adequate for singularly perturbed reaction-diffusion problems since it can not efficiently reflect the behaviour of the boundary layer parts when the diffusion coefficient is very small. For the first time, the error estimates in the balanced norm has been presented for a system of coupled singularly perturbed problems when each equation has different parameter. Optimal and uniform error estimates have been established in the energy and balanced norm on an uniform Shishkin mesh. Finally, we carry out various numerical experiments to verify the theoretical findings.