Inhomogeneous shape distributions and size effects in jammed deformable microgel dispersions under microchannel flow

The flow behavior of jammed monodisperse microgel dispersions in a narrow microchannel is examined using Dissipative Particle Dynamics, with emphasis on the roles of microgel size and deformation. Larger microgels produce a higher maximum velocity in the velocity profile and reach lower values of the local apparent viscosity at the same shear rate. Relating to the Herschel–Bulkley model, this size effect appears mainly as a decrease in the material constant k , whereas the flow index and yield stress ( n and τ y ) remain nearly insensitive to size. Despite differences in absolute velocity, all normalized velocity profiles from both simulations and experiments collapse onto a single universal master curve, showing flow universality across different microgels. This universality is associated with shear-rate-dependent and strongly inhomogeneous deformation across the channel, where particles in high-shear regions experience pronounced stretching. Larger microgels, being more compressible and deformable, display more pronounced stretching and thus experience lower flow resistance, while variations in deformation are reflected mainly in the material constant k .