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PLEASE NOTE: If a candidate gives a layman's talk, the livestream will start fifteen minutes earlier.

Colloidal gels are materials made when tiny particles suspended in a liquid stick together to form a fragile, sponge-like network. Although mostly liquid, these networks give gels solid-like properties, which makes them useful in everyday products such as food, cosmetics, and coatings. Despite their importance, how the microscopic structure of a gel determines its large-scale behavior is still not well understood.

This thesis combines advanced computer simulations with theoretical modeling to uncover the physics of colloidal gels. A major part of the work is the development of a new simulation tool, JFSD, a modern and efficient implementation of Fast Stokesian Dynamics. This allows us to simulate thousands of particles interacting through the surrounding fluid with high accuracy. With this method, we show how hydrodynamic interactions — the subtle ways particles influence each other through the liquid — play a key role in the formation and aging of gels.

Building on these insights, we extend existing theories of gel gravitational collapse by introducing new microscopic ingredients, such as a local viscosity that describes how the network resists deformation. This leads to predictions of new timescales for collapse that were missed by earlier models. Finally, we establish a direct link between simulations and experiments by initialising our models with particle positions obtained from confocal microscopy.

Overall, this thesis provides new tools and concepts for understanding how colloidal gels form, evolve, and eventually fail, insights that are also relevant for soft matter systems ranging from industrial formulations to biological tissues.