Thermal Fluctuations in a Layer of Liquid Subjected to Temperature Gradients with and without the Influence of Gravity

Abstract

We report data for nonequilibrium density fluctuations in a layer of liquid CS 2 subjected to temperature gradients on Earth and in a satellite. The structure factor S (q) was measured using a calibrated shadowgraph. Upon removing gravity, S (q) increased dramatically at small wave vector, until the fluctuations generated by thermal noise were limited only by the 3 mm sample thickness. The results agree with theory to within a few percent on Earth and are∼ 14% below theory in microgravity, demonstrating that the use of equilibrium Langevin forces is appropriate in this nonequilibrium situation.

Roberto Cerbino

Professor of Experimental Soft Matter Physics

My research interests include Soft matter physics, living matter, cell biophysics and quantitative microscopy.