BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Constitutive mechanical relations of a partially molten rock in te
 rms of grain boundary contiguity: an approach with an internal state varia
 ble - Yasuko Takei (University of Tokyo)
DTSTART:20160412T103000Z
DTEND:20160412T113000Z
UID:TALK65413@talks.cam.ac.uk
CONTACT:INI IT
DESCRIPTION:Mechanical and transport properties of a partially molten rock
  strongly depend on the grain scale melt geometry. To quantify the microst
 ructural effects\, constitutive mechanical relations for elasticity (Takei
 \, 1998) and diffusion creep viscosity (Takei and Holtzman\, 2009) are der
 ived theoretically by considering a realistic microstructural model. The e
 ssential geometrical factor which determines these properties was found to
  be the ``grain boundary contiguity&rsquo\;&rsquo\; which represents the a
 rea of grain-to-grain contacts relative to the total surface area of each 
 grain. One of the most striking results is that while contiguity affects b
 oth elasticity and viscosity\, the effect on viscosity is about 100 times 
 larger than that on elasticity. When partially molten rock is texturally e
 quilibrated\, contiguity is determined as a function of melt fraction and 
 dihedral angle. However\, when it is deformed under a deviatoric stress\, 
 contiguity deviates from the equilibrium value an d evolves\, resulting in
  a significant change in the matrix viscosity. Possible consequences of th
 ese microstructural evolution on the macroscopic dynamics can be studied w
 ithin the framework of continuum mechanics by solving the governing equati
 ons of two phase flow together with the viscous constitutive relation whic
 h includes contiguity as an internal state variable. By applying this appr
 oach to the formation of stress-driven\, melt-enriched channels\, I will d
 emonstrate the important role of microstructural processes in the macrosco
 pic dynamics.
LOCATION:Seminar Room 1\, Newton Institute
END:VEVENT
END:VCALENDAR