Two different 'a posteriori' error estimation techniques are proposed
in this paper. The effectiveness of the error estimates in adaptive me
sh refinement for 2D and 3D electrostatic problems are also analyzed w
ith numerical test results. The post-processing method employs an impr
oved solution to estimate the error, whereas the gradient of field met
hod utilizes the gradient of the field solution for estimating the 'a
posterior' error. The gradient of field method is computationally inex
pensive, since it solves a local problem on a patch of elements. The e
rror estimates are tested by solving a set of self-adjoint boundary va
lue problems in 2D and 3D using a hierarchical minimal tree based mesh
refinement algorithm. The numerical test results and the performance
evaluation establish the effectiveness of the proposed error estimates
for adaptive mesh refinement.