Willem Prins Lecture 2015 given by Prof. dr. A.N. Beris

The Willem Prins lecture of 2015 entitled Nonequilibrium thermodynamics modeling of the flow and deformation of complex materials with internal microstructure was given by prof. dr. A. N. Beris from the University of Delaware (CV). Prof. Beris was chosen for his outstanding contributions concerning the application of non-equilibrium thermodynamics to polymer systems. The lecture was given during the 7th International Workshop on Nonequilibrium Thermodynamics (IWNET2015) that was held in Hilvarenbeek, the Netherlands.   Willem Prins
Summary
In this lecture a review of modern developments in the use of the nonequilibrium thermodynamics framework to model the dynamics of complex materials with internal microstructure was offered. An essential part in the modeling the dynamics of complex materials is the specification of additional, non-equilibrium, internal, structural state variables that, together with those used under equilibrium conditions, serve to fully characterize the nonequilibrium state of the system under consideration. The choice of the variables is then followed by a description of the system’s total energy and entropy (or, alternatively, the Helmholtz free energy) through a specification of suitable functionals and a prescription of the reversible and irreversible (dissipative) dynamics in terms of the specification of corresponding brackets or matrix operators. That much has been known since the pioneering work of Grmela and described in detail in several textbooks. What we like to address here are some recent macroscopic example applications.
Most of the success in previously developed applications involved polymeric and/or liquid crystalline systems with respect to which a single conformation or orientation tensor parameter was sufficient to describe the observed phenomena. What we will like to address in this presentation are models requiring more than a single internal structural parameter and/or more than one transport phenomena (typically a coupling of flow with mass transfer) in order to describe a more complex microstructure. In particular, we will illustrate the challenges and opportunities posed in describing this inherently much more complex behavior in three modern examples: (i) concentrated colloidal systems, (ii) wormlike micellar systems, and (iii) entangled polymer solutions or melts. Finally, the connection to shear banding phenomena and material discontinuities is going to be discussed.