Tj Timo Faber

Kinetic model for the mechanical response of suspensions of sponge-like particles

A dynamic two-scale model is developed that describes the stationary and transient mechanical behavior of concentrated suspensions made of highly porous particles. Particularly, we are interested in particles that not only deform elastically, but also can swell or shrink by taking up or expelling the viscous solvent from their interior, leading to rate-dependent deformability of the particles. The fine level of the model describes the evolution of particle centers and their current sizes, while the shapes are at present not taken into account. The versatility of the model permits inclusion of density- and temperature-dependent particle interactions, and hydrodynamic interactions, as well as to implement insight into the mechanism of swelling and shrinking. The coarse level of the model is given in terms of macroscopic hydrodynamics. The two levels are mutually coupled, since the flow changes the particle configuration, while in turn the configuration gives rise to stress contributions, that eventually determine the macroscopic mechanical properties of the suspension. Using a thermodynamic procedure for the model development, it is demonstrated that the driving forces for position change and for size change are derived from the same potential energy. The model is translated into a form that is suitable for particle-based Brownian dynamics simulations for performing rheological tests. Various possibilities for connection with experiments, e.g. rheological and structural, are discussed.

Modeling structure-sensory texture relations in semi-hard cheese

Product and process design in the food industry often still remains a very empirical activity. This will not lead to leap changes in product functionality or composition. We aim at developing quantitative models which relate the microstructure of semi-hard cheese to sensory texture. With these models we want to design more resource efficient process routes and healthier options for full fat semi-hard cheese. In this paper the role of multi-scale simulations using a Finite Element Method in developing these models will be discussed.