EXPERIMENTAL STUDY ON THE MOTION OF MICRON-SIZED PARTICLES IN VISCOELASTIC FLUIDS THROUGH SERPENTINE MICROCHANNELS

This study investigates the migration behavior of particles in serpentine microchannels with constant curvature using various viscoelastic fluids (polyvinylpyrrolidone aqueous solutions) under low Reynolds number (Re) conditions. Compared to straight channels, particle dynamics in serpentine channels must additionally account for the drag force induced by secondary flow. The viscoelasticity of the fluids promotes particle focusing toward the channel center, an effect that strengthens with increasing particle size and flow rate. Under the dynamic balance of inertial lift, drag, and elastic forces, particles achieve stable three-dimensional focusing in a varying flow field. Among the different viscoelastic fluids tested, the 8.0 wt% PVP + 18.6 wt% glycerol aqueous solution, possessing higher viscosity, exhibits weakened secondary flow intensity, resulting in relatively dispersed particle distribution and poorer focusing performance within the microchannel. These findings contribute to a deeper understanding of particle migration and focusing behavior in serpentine microchannels, providing a theoretical basis for the design and optimization of microfluidic chips.