Numerical simulations on the dynamics of trains of particles in a viscoelastic fluid flowing in a microchannel

The formation of equally-spaced structures (trains) of rigid, spherical particles suspended in a viscoelastic fluid flowing in a cylindrical microchannel is investigated by numerical simulations. Direct Numerical Simulations (DNS) have been employed to accurately compute the translational velocities of a system made by three particles aligned along a cylindrical channel for different interparticle distances. A shear-thinning, elastic fluid, modeled by the Giesekus costitutive equation, is considered. The DNS results are collected in a database used for simulating the dynamics of a multi-particle system. The evolution of the particle microstructure through the channel is presented in terms of interparticle distance distributions. The effects of the Deborah number (defined as the ratio between the fluid and flow characteristic times), the volume fraction, and the initial particle distribution on the train dynamics are investigated.