A robust numerical method for a coupled system of singularly perturbed parabolic delay problems

Purpose The purpose of this paper is to design and analyze a robust numerical method for a coupled system of singularly perturbed parabolic delay partial differential equations (PDEs). Design/methodology/approach Some a priori bounds on the regular and layer parts of the solution and their derivatives are derived. Based on these a priori bounds, appropriate layer adapted meshes of Shishkin and generalized Shishkin types are defined in the spatial direction. After that, the problem is discretized using an implicit Euler scheme on a uniform mesh in the time direction and the central difference scheme on layer adapted meshes of Shishkin and generalized Shishkin types in the spatial direction. Findings The method is proved to be robust convergent of almost second-order in space and first-order in time. Numerical results are presented to support the theoretical error bounds. Originality/value A coupled system of singularly perturbed parabolic delay PDEs is considered and some a priori bounds are derived. A numerical method is developed for the problem, where appropriate layer adapted Shishkin and generalized Shishkin meshes are considered. Error analysis of the method is given for both Shishkin and generalized Shishkin meshes.

A Novel Technique for Constructing Difference Schemes for Systems of Singularly Perturbed Equations

In this paper, we propose a novel and simple technique to construct effective difference schemes for solving systems of singularly perturbed convection-diffusion-reaction equations, whose solutions may display boundary or interior layers. We illustrate the technique by taking the Il'in-Allen-Southwell scheme for 1-D scalar equations as a basis to derive a formally second-order scheme for 1-D coupled systems and then extend the scheme to 2-D case by employing an alternating direction approach. Numerical examples are given to demonstrate the high performance of the obtained scheme on uniform meshes as well as piecewise-uniform Shishkin meshes.

A FEM FOR A SYSTEM OF SINGULARLY PERTURBED REACTION-DIFFUSION EQUATIONS WITH DISCONTINUOUS SOURCE TERM

In this paper, we consider a weakly coupled system of two reaction-diffusion equations with discontinuous source terms. When a parameter multiplying the second order derivatives in the equations is small, their solutions exhibit boundary layers as well as interior layers. A numerical method based on finite element and Shishkin and Bakhvalov–Shishkin meshes is presented. We derive an error estimate of order O(N-1ln N) in the energy norm with respect to the perturbation parameter. Numerical experiments are also presented to support our theoritical results.

COMPARISON OF ADAPTIVE MESHES FOR A SINGULARLY PERTURBED REACTION–DIFFUSION PROBLEM

We consider a singular second-order boundary value problem. The differential problem is approximated by the Galerkin finite element scheme. The main goal is to compare the well known apriori Bakhvalov and Shishkin meshes with the adaptive mesh based on the aposteriori dual error estimators. Results of numerical experiments are presented.