Multiscaling to standard-scaling crossover in the Bray-Humayun model for phase-ordering kinetics

The Bray-Humayun model for phase-ordering dynamics is solved numerically in one and two space dimensions with conserved and nonconserved order parameter. The scaling properties are analyzed in detail, and we find the crossover from multiscaling to standard scaling in the conserved case. Both in the nonconserved case and in the conserved case, when standard scaling holds an exponential tail in the scaling function is found.