Berlin 2008 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 20: POSTERS Driven Soft Matter

CPP 20.15: Poster

Wednesday, February 27, 2008, 16:00–18:30, Poster A

Effects of spatio-temporal forcing on phase separation — •Vanessa Weith, Alexei Krekhov, and Walter Zimmermann — Theoretische Physik I, Universität Bayreuth, 95440 Bayreuth, Germany

Motivated by recent experiments on polymer blends with a large Soret effect [1,2] we have studied phase separation in the presence of an inhomogeneous temperature field. Within a generalized Cahn-Hilliard model [3] we have investigated the effects of an additive spatio-temporal forcing ∼ a cos(qx−vt) on phase separation, which corresponds to a spatio-temporal temperature modulation in optical grating experiments [1,2].

For a stationary forcing with v=0 one finds that beyond a critical forcing amplitude a₀(q) spinodal decompostion is locked by the spatially periodic forcing. We show how this critical locking amplitude is changed by increasing the pulling velocity v. Furthermore we identify the changes of the bifurcation to the spatially periodic patterns as a function of v and we present results about the spatio-temporal behavior of the solution of the generalized Cahn-Hilliard model in one and two spatial dimensions.

[1] S. Wiegand and W. Köhler, in Thermal Nonequilibrium Phenomena in Fluid Mixtures, edited by W. Köhler and S. Wiegand (Springer, Heidelberg, 2002)

[2] W. Enge and W. Köhler, Phys. Chem. Chem. Phys. 6, 2373 (2004)

[3] A. P. Krekhov and L. Kramer, Phys. Rev. E 70, 061801 (2004)