Yield surface of attractive colloidal gels under Poiseulle flow

Short-ranged attractive colloidal systems that assemble into gels exhibit a series of exotic rheological behavior, including emergence of a yield stress. The yielding mechanism of these colloidal gels under simple drag flows have been studied extensively over the past decade or so. Nonetheless, the porous and heterogeneous structure of these gels results in presence of a yield surface under pressure-driven flows, aka Poiseulle flow. Due to heterogeneous deformation rates that develop in Poiseulle flow, the interactions between the flow boundaries and the colloids also play an important role in the structure/assembly of colloids and their resulting rheology. In this work, yielding behavior of colloidal gels at Φ=20% confined between two walls under Poiseuille flow is computationally studied for attractive and repulsive interactions between the walls and the colloidal particles. We find that the entire range of shear-induced structures: compaction, re-structuration and coarsening, and shear rejuvenation are present in the Poiseulle flow of the colloidal gels. We compare these observed regimes with the ones previously reported for the simple shear flows and benchmark the structural evolutions of the system against those previous studies.