  When colloids flow in a narrow channel, the transport efficiency is
controlled by the non-equilibrium interplay between colloid-wall interactions
and hydrodynamics. In this paper, a general, unifying description of colloidal
dispersion flow in a confined system is proposed. A momentum and mass balance
founded framework implementing the colloid-interface interactions is
introduced. The framework allows us to depict how interfacial forces drive the
particles and the liquid flows. The interfacially driven flow (osmotic or
Marangoni flows for repulsive or attractive colloid-wall interactions
respectively) can be directly simulated in two-dimensional domains. The ability
of the model to describe the physics of transport in a narrow channel is
discussed in detail. The hydrodynamic nature of osmosis and the associated
counter-pressure are mechanically related to the colloid-interface
interactions. The simulation shows an unexpected transition from axial plug to
pillar accumulation for colloidal accumulation at a channel bottleneck. This
transition has important consequences in transport efficiencies. Existing
limiting cases, such as diffusio-osmosis, are recovered from the simulations,
showing that the framework is physically well-founded. The model generalizes
the existing approaches and proves the hydrodynamic character of osmosis, which
cannot be fully described by purely thermodynamic considerations.
