  The three-dimensional microstructure of Ni, observed after five annealing
intervals, was compared to simulations of grain growth using the threshold
dynamics method with the assumption of capillarity as the only driving force. A
grain-by-grain comparison made it possible to identify the sources of
differences between the simulation and experiment. The most significant
difference was for grains of the smallest sizes, which the simulation predicted
would lose volume and disappear at a greater rate than observed in the
experiment. The loss of grains created errors in the numbers of neighbors of
the remaining grains, and it was found that errors in the simulated grain
volume were correlated to errors in the number of near neighbors. While
anisotropic grain boundary properties likely play a role in the differences,
the size dependence of the errors suggest that it might be necessary to include
a size dependence in the model for grain boundary migration kinetics.
