Pattern Selection near the Onset of Convection: The Eckhaus Instability

Abstract

We present an experimental study of the space and time evolution of the Eckhaus instability, a general mechanism of pattern selection for spatially periodic patterns in nonlinear systems. Using a convecting liquid crystal layer, we observed long-wavelength modulations leading to the nucleation of new roll pairs. The development of this process is studied by time-resolved spatial Fourier analysis and compared with predictions based on an amplitude equation.