| Complex fluids are ubiquitous in science and engineering. Biological fluids, immiscible blends, foams, and many types of suspensions are familiar examples of complex fluids. Their internal structure (e.g. suspended particles in suspensions or the interface in immiscible blends) evolves in time on the time scale that is comparable with the time scale of the macroscopic motion. The macroscopic time evolution has to be therefore coupled to the microstructure time evolution. Such coupling then causes the complexity of the flow phenomena.;This thesis focuses on suspensions of interfaces or elastic membranes. They include the clean interface between two liquid bulks, liquid interfaces covered with surface active agents, and solid-liquid membranes of red blood cells. The popular point of departure of a theoretical analysis of this type of complex fluids is microhydrodynamics. The formulation can either be made into a basis for direct numerical simulations or it can be carried to a field formulation. In both cases an extensive computer power is needed to solve the governing equation. To pass finally to predictions of flow properties one needs to involve still an additional physics and approximations that allow to transform the solutions (addressing typically trajectories of individual particles or a single particle deformations) into stresses arising in the fluids.;The approach that we use in this thesis is mesoscopic. The starting point is a. mesoscopic model of the internal structure and of the physics taking place in the fluid. The physics is then expressed into governing equations of the rheological model by following the thermodynamic (GENERIC) framework. In most cases, the governing equations are just a set of ordinary differential equations that can readily be solved by using a standard software. Predictions of our models are found to be in a good agreement with results of experimental observations and predictions of the models based on microhydrodynamics. |
