The evolution of a surface intersected by transgranular (TG) and intergranular (IG) edge voids under isotropic surface diffusion and electric field effects is simulated numerically under both mass-conserving and non-mass-conserving boundary conditions. A surprising similarity is found in the surface topology of transgranular voids between our non-mass-conserving model and Schimschak and Krug's [J. Appl. Phys. 87 (2000) 695] mass-conserving model. The electric field is found to slow the development of an intergranular groove along a positively tilted grain boundary (GB), and to cause thinning or thickening of grains under non-mass-conserving conditions. (C) 2004 Elsevier B.V. All rights reserved.