Noise sustained pattern growth: Bulk versus boundary effects

The effect of thermally generated bulk stochastic forces on the statistical growth dynamics of forwards bifurcating propagating macroscopic patterns is compared with the influence of fluctuations at the boundary of a semiinfinite system, $0<x$. To that end the linear complex Ginzburg-Landau amplitude equation with additive stochastic forcing is solved by a spatial Laplace transformation in the presence of arbitrary boundary conditions for the fluctuations of the pattern amplitude at $x=0$. A situation where the latter are advected with an imposed through-flow from an outside upstream part towards the inlet boundary at $x=0$ is investigated in more detail. The spatiotemporal growth behavior in the convectively unstable regime is compared with recent work by Swift, Babcock, and Hohenberg [Physica A 204, 625 (1994)] where a special boundary condition is imposed.