  Colloidal gels are elasto-plastic materials composed of an
out-of-equilibrium, self-assembled network of micron-sized (solid) particles
suspended in a fluid. Recent work has shown that far-field hydrodynamic
interactions do not change gel structure, only the rate at which the network
forms and ages. However, during gel formation, the interplay between
short-ranged attractions leading to gelation and equally short-ranged
hydrodynamic lubrication interactions remains poorly understood. Here, we
therefore study gelation using a range of hydrodynamic descriptions: from
single-body (Brownian Dynamics), to pairwise (Rotne-Prager-Yamakawa), to
(non-)lubrication-corrected many-body (Stokesian Dynamics). We confirm the
current understanding informed by simulations accurate in the far-field. Yet,
we find that accounting for lubrication can strongly impact structure at low
colloid volume fraction. Counterintuitively, strongly dissipative lubrication
interactions also accelerate the aging of a gel, irrespective of colloid volume
fraction. Both elements can be explained by lubrication forces facilitating
collective dynamics and therefore phase-separation. Our findings indicate that
despite the computational cost, lubricated hydrodynamic modeling with many-body
far-field interactions is needed to accurately capture the evolution of the gel
structure.
