Domain Coarsening in Systems Far from Equilibrium

The growth of domains of stripes evolving from random initial conditions is studied in numerical simulations of models of systems far from equilibrium such as Rayleigh-Bénard convection. The size of the domains deduced from the inverse width of the Fourier spectrum is found to scale as $t^{1/5}$ for both potential and nonpotential models. The morphology of the domains and the defect structures are, however, quite different in the two cases, and evidence is presented for a second length scale in the nonpotential case growing as $t^{1/2}$.