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Phase separation of binary mixtures in shear flow : a numerical study
Full text linkThe phase-separation kinetics of binary fluids in shear flow is studied numerically in the framework of the continuum convection-diffusion equation based on a Ginzburg-Landau free energy. Simulations are carried out for different temperatures both in d=2 and 3. Our results confirm the qualitative picture put forward by the large-Rr limit equations studied by Corberi et al. [Phys. Rev. Lett. 81, 3852 (1998)]. In particular, the structure factor is characterized by the presence of four peaks whose relative oscillations give rise to a periodic modulation of the behavior of the rheological indicators and of the average domains sizes. This peculiar pattern of the structure factor corresponds to the presence of domains with two characteristic thicknesses, whose relative abundance changes with time
Two-scale competition in phase separation with shear
No full textThe behavior of a phase separating binary mixture in uniform shear flow is investigated by numerical simulations and in a renormalization group approach. Results show the simultaneous existence of domains of two characteristic scales. Stretching and cooperative ruptures of the network produce a rich interplay where the recurrent prevalence of thick and thin domains determines log-time periodic oscillations. A power-law growth R(t) similar to t(alpha) of the average domain size, with alpha = 4/3 and alpha = 1/3 in the flow and shear direction, respectively, is shown to be obeyed
The segregation of sheared bynary fluids in the Bray-Humayun model
No full textThe phase separation process which follows a sudden quench
inside the coexistence region is considered for a binary
fluid subjected to an applied shear flow.
This issue is studied in the framework of the convection-diffusion equation
based on a Ginzburg-Landau free energy functional in the
approximation scheme introduced by
Bray and Humayun [Phys. Rev. Lett. 68, 1559 (1992)].
After an early stage where domains form and shear effects become
effective the system enters a scaling regime where the typical domains
sizes ,
along the flow and perpendicular to it
grow as and . The structure factor is characterized
by the existence of four peaks, similarly to previous theoretical
and experimental observations, and by exponential tails at large wavevectors
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