Amplification of Thermal Noise via Convective Instability in Binary-Fluid Mixtures

In the convectively unstable regime of a binary-fluid mixture in a quasi-one-dimensional ramped convection channel an erratic spatio-temporal behaviour of very small amplitudes is observed. These patterns are interpreted as the amplification of intrinsic noise. Their measured temporal correlation functions are compared with the theoretical ones obtained from a Ginzburg-Landau equation containing a noise term. The measured intensity confirms the assumption that the fluctuations are due to thermal noise.