The Bray-Humayun model for phase ordering dynamics is solved numerically in
one and two space dimensions with conserved and non conserved order parameter.
The scaling properties are analysed in detail finding 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 the
novel feature of an exponential tail in the scaling function is found.Comment: 21 pages, 10 Postscript figure