THE LEVICH INSTITUTE ANNOUNCES THE FOLLOWING SEMINAR

Tuesday, 10/20/98
4:00 PM
Steinman Hall, Room #1M-22
Professor Roberto Mauri
City College of CUNY
Chemical Engineering Department
"Phase Separation of Deeply Quenched Liquid Mixtures "


ABSTRACT

After quenching a partially miscible, initially homogeneous liquid mixture to a temperature deeply below its critical point of miscibility, we observe the formation of microdomains, which grow linearly in time within the range of 10 to 400 microns, indicating that phase segregation is driven by convection, and not by diffusion. While these domains are interconnected dendritic structures when the mixture has critical composition, they appear to be spherical drops in the off-critical case. These experimental results were modeled following the standard model H, where convection and diffusion are coupled via a body force which, in the limit of sharp interfaces separating single-phase domains, reduces to the capillary interaction. This force induces a material flux which larger than that due to pure molecular diffusion, as in a typical case the Peclet number is of the order 10⁴. The 2D computer simulations based on this theoretical model capture the physics of the phenomenon of phase separation drops, in agreement with the experimental results. In addition, when simulating the behavior of a single drop in a uniform continuum field, the model predicts that it moves randomly as it grows, with a typical speed which scales with the ratio between molecular diffusivity and interfacial thickness.


Return to Fall, 1998 Seminar Schedule