|Project heads||Dirk Peschka ★, Matthias Rosenau ✻, Marita Thomas ★, Barbara Wagner ★|
|Staff||Xin Liu ★|
|Institutes||★ Weierstrass Institute, ✻ GFZ (Helmholtz-Zentrum Potsdam)|
Acknowledgement: This research is carried out in the framework of the DFG funded Cluster of Excellence EXC 2046 MATH+: The Berlin Mathematics Research Center within the Application Area Materials, Light and Devices. The funding period of the project is from January 2021 until December 2022.
Background and goals
The goal of the MATH+ project AA2-9 Variational methods for viscoelastic flows and gelation is to study continuum formulations for flows of elastic particles immersed in a liquid and their gelation by variational modeling, mathematical analysis, and structure-preserving discretizations. The resulting models will be calibrated using experimental data. Flows of soft elastic particles suspended in viscous fluids play a fundamental role in biological and geological systems. In microgel suspensions, they offer promising future prospects for engineering and pharmaceutical industries. The viscoelastic properties of these systems vary depending on the particle density: At low densities (dilute regime) mixtures have an effective viscosity and elastic properties are negligible, while for moderate densities (dense regime) particles interact and deform so that the effective flow becomes viscoelastic; such a viscous or viscoelastic suspension is called (sol). As the suspension exceeds the dense regime, solid particles become so densely packed that elastic links are formed between them; such a mixture is called (gel). Although this sol-gel transition is not yet well-understood, its vital impact on soft matter, biological or medical applications is evident: Examples are plaque formation and drying blood, where platelets enter a condensed aggregate phase, or suspensions of proteins in electrolyte solutions that are prone to form gels by clustering. For these systems the elasticity enters the models via the elastic properties of the particles themselves and via the rheology of the assembled gel. From a mathematical point of view, these models have an intriguing interplay of Lagrangian and Eulerian descriptions, where the availability of corresponding transformation maps is a central open question. In the proposed project we will develop a unified continuum model based on phase indicators for the fluid and the solid phase that encompasses the behavior of both regimes (sol) and (gel) and captures the phase transition from one to the other.