Buoyancy-Driven Instability in a Dilute Solution of Macromolecules

Abstract

We have performed optical measurements on a hydrodynamic instability occurring in a dilute polymer solution characterized by a negative value of the thermal diffusion ratio and heated from above. We determine the threshold condition and the behavior of the convected mass flow above threshold. Qualitative evidence of critical slowing down is also reported together with a discussion on the convective-mode wavelength.