FLUID CIRCULATION AND SOLUTE DISTRIBUTION IN A BINARY-FLUID MIXTURE -SELF-ORGANIZATION UNDER OSMOSEDIMENTATION

In this work a theoretical analysis of the osmosedimentation process i s presented. We investigate the role played by small-density non-unifo rmities in inducing fluid circulation and mass transport in a viscous binary mixture under a strong centrifugal field. We find that a Boussi nesq term considered in the momentum equation is of fundamental import ance in the convection-diffusion process. The strong centrifugal force s that develop in the solution as a result of the small-density inhomo geneities are responsible for the emergence of a dissipative structure : the fluid can show a complex arrangement of convection cells leading to solute mass redistribution. Time evolution of the cell patterns (c onvection cells and solution concentration cells) during the first sta ges of the osmosedimentation process is presented. The results are sig nificant as a clue for understanding pattern formation in systems inve stigated in the laboratory. (C) 1998 Elsevier Science B.V. All rights reserved.