Asymmetric oscillations during phase separation under continuous cooling: A simple model.
We investigate the phase separation of binary mixtures under continuous cooling using the Cahn-Hilliard equation including the effect of gravity. In our simple model, sedimentation is accounted for by instantaneously "removing" droplets from the supersaturated mixture into the coexisting phase once the droplets have reached a defined maximum size. Our model predicts an oscillatory variation of turbidity. Depending on the composition, either both phases oscillate (symmetric oscillations) or only one of the phases oscillates (asymmetric oscillations). In the asymmetric case, droplet sedimentation from the majority phase into the minority phase reduces supersaturation in the minority phase. This inhibits droplet formation in the minority phase. The cooling rate dependence of the period agrees with experimental results.
Hayase
Yumino
Y
Max Planck Institute for Polymer Research, 55128 Mainz, Germany. hayase@mpip-mainz.mpg.de
Kobayashi
Mika
M
Vollmer
Doris
D
Pleiner
Harald
H
Auernhammer
Günter K
GK