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INVITED TALK
Session: 4 Complex fluid deformation and rheology: Theories and thermodynamic relationships
(scheduled: Tuesday, 08:00 )
Dynamic van der Waals theory
A. Onuki
Physics Department, Kyoto University, Japan
We present a dynamic van der Waals theory including gradient entropy and energy. We introduce the temperature as a functional of the number density and the energy density. Our model is useful to study phase separation when the temperature varies in space. As an example, we show that if heat flow is applied to liquid suspending as droplet at zero gravity, a convective flow occurs such that the temperature gradient within the droplet nearly vanishes. As the heat flux is increased, the droplet becomes attached to the heated boundary that is wetted by liquid in equilibrium. In one case corresponding to partial wetting by gas, an apparent contact angle can be defined. In the other case with larger heat flux, the droplet completely wets the heated boundary expelling liquid. As another example, we study wetting dynamics with evaporation and condensation. © IWNET 2006
[1] A. Onuki, Phys. Rev. Lett. 94 (2005), 054501.
ORAL PRESENTATION
Session: 4 Complex fluid deformation and rheology: Theories and thermodynamic relationships
(scheduled: Tuesday, 10:45 )
Plastic flow of solids
A. Minami, A. Onuki
Department of Physics, Kyoto University, Kyoto 606-8502, Japan
A phase field model is presented to study dislocation formation (coherency loss) in one- and two-phase binary alloys. In our model, the elastic energy density is a periodic function of the strain components, which allows multiple formation of dislocations. The composition is coupled to the elastic field twofold via lattice misfit and via composition-dependence of the elastic moduli. By numerically integrating the dynamic equations in two and three dimensions, we find that dislocations appear in pairs in the interface region in two dimensions and as a loop with the ends trapped at the interface in three dimensions. They glide under uniaxial stretching in the softer region and do not penetrate into the harder domains. This process gives rise to a plastic flow, where stress increases gradually with increasing applied strain. Particularly in three dimensions, we follow the dislocation loop formation and growth around hard domains. We also observe growth of spiral-shaped domains rich in the softer component around screw dislocations. © IWNET 2006
[1] Akihiko Minami and Akira Onuki ''Dislocation formation and plastic flow in binary alloys in three dimensions'' Phys. Rev. B 72, 100101(R) (2005).
[2] Akihiko Minami and Akira Onuki, ''Dislocation formation in two-phase alloys'' Phys. Rev. B 70, 184114 (2004).
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and Kleanthi for IWNET 2006