The Influence Effect of Fluid Elasticity on Particle Aggregation in Microchannels

The relative motion model was employed for numerical simulation of particle aggregation in viscoelastic fluids, with the OldroydB model to describe the viscoelastic constitutive relationship and the logconformation reformulation for stable numerical simulation. The effects of particle aggregation characteristics on viscoelastic fluids with varying elasticities were examined. The findings show that, an increase in the Weissenberg number (Wi), coupled with a reduction in the β value of the viscoelastic fluid, could substantially enhance the fluid elasticity within the channel. Furthermore, significant fluctuations in the force experienced at the radial positions of the particles were observed. The distribution of radial forces on the particles fundamentally depends on the distribution of inertial forces, with elastic lifts fluctuations also causing inertial lift variations; thus, inertia and elasticity coexist nonlinearly. Higher Wi and lowerβvalues enlarge the region where lift forces direct particles toward the pipe center, shifting aggregation from the wall toward the center. In addition, the strong elastic flow makes the force direction of the particles always point to the pipe center.