Rob Campbell Proceeds to PhD Candidacy

Congratulations to Rob Campbell on passing the oral Ph.D. qualifying exam and becoming a Ph.D. candidate!

Rob presented on the development of models for 3-stage gravitational collapse in colloidal gels. The presentation started from a constitutive model based on poroelasticity, incorporating information about network structure and fluid pressure into our understanding of gel compaction. It then proceeded to show how a phase-diagram-based analysis reveals how gravitational effects are tied to particle size and total network yield stress, suggesting the rapid middle stage of collapse is the result of long-range hydrodynamics and network break up. Finally, research using large-scale simulations was able to reproduce 3-stage collapse as a purely network-dynamics-based phenomenon, where osmotic pressure drives a non-equilibrium phase separation. The results point to the significance of particle size, network structure, and network dynamics in colloidal gel rheology, but leave open questions on the effect of long-range hydrodynamics and the best ways to prevent collapse.

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