Comment on "Phase ordering in chaotic map lattices with conserved dynamics"

Angelini, Pellicoro, and Stramaglia [Phys. Rev. E 60, R5021 (1999)] claim that the phase ordering of two-dimensional systems of sequentially updated chaotic maps with conserved "order parameter" does not belong, for large regions of parameter space, to the expected universality class. We show here that these results are due to a slow crossover and that a careful treatment of the data yields normal dynamical scaling. Moreover, we construct better models, i.e., synchronously updated coupled map lattices, which are exempt from these crossover effects, and allow for precise estimates of persistence exponents in this case.