Nina Kirchner

Thermodynamics of Segregating Granular Mixtures.

Abstract: A striking phenomenon to be observed e.g. in (natural, industrial and laboratory) avalanches is the effect of ``inverse grading'': during the avalanching motion, the individual particles forming the body of the avalanche are re-distributed in such a way that large particles gather on top and at the front, while small particles concentrate close to the bottom and the rear. This segregation according to particle size has been our motivation to develop a thermodynamically consistent continuum-mechanical model which is applicable to granular mixtures consisting of a finite number of constituents. The thermo-mechanical model is characterised by N additional evolution equations of ``configurational force-type'' for N scalar-valued, internal variables: the volume fractions of the constituents. Moreover, a partial abandonment of the principle of phase separation is suggested to account for interactions between various constituents on the constitutive level. The main results obtained from a rigorous exploitation of the entropy principle according to Mueller & Liu are presented and discussed.