  We study the late stages of spinodal decomposition in a Ginzburg-Landau mean
field model with quenched disorder. Random spatial dependence in the coupling
constants is introduced to model the quenched disorder. The effect of the
disorder on the scaling of the structure factor and on the domain growth is
investigated in both the zero temperature limit and at finite temperature. In
particular, we find that at zero temperature the domain size, $R(t)$, scales
with the amplitude, $A$, of the quenched disorder as $R(t) = A^{-\beta}
f(t/A^{-\gamma})$ with $\beta \simeq 1.0$ and $\gamma \simeq 3.0$ in two
dimensions. We show that $\beta/\gamma = \alpha$, where $\alpha$ is the
Lifshitz-Slyosov exponent. At finite temperature, this simple scaling is not
observed and we suggest that the scaling also depends on temperature and $A$.
We discuss these results in the context of Monte Carlo and cell dynamical
models for phase separation in systems with quenched disorder, and propose that
in a Monte Carlo simulation the concentration of impurities, $c$, is related to
$A$ by $A \sim c^{1/d}$.
