Experimental Study of Viscoelastic Suspension Flow Over Textured Surfaces

The migration and organization of inertial particles in viscoelastic flows are governed by a complex interplay between fluid elasticity, inertia, and channel geometry. While prior studies have extensively examined particles focusing on Newtonian and dilute viscoelastic fluids, much less is known about migration behavior in viscoelastic suspensions at moderate volume fractions, particularly in the presence of wall textures that can induce secondary flows.

In this work, we investigate laminar viscoelastic flows of both pure fluids and dilute particle-laden suspensions in a channel with surface textures. Using particle image velocimetry (PIV) and particle tracking, we analyze the flow fields and particle concentration profiles for suspensions of neutrally buoyant PMMA particles in a 300ppm polyacrylamide solution. Preliminary observations suggest that textured walls significantly modify near-wall velocity gradients and particle migration patterns, even at low Reynolds numbers (Re ~ 1–100). These effects are changed by elasticity (Weissenberg numbers up to 20) and volume fractions up to 0.1. The emerging migration patterns appear to result from a combination of shear-induced lift, groove-driven secondary flows, and elastic normal stresses.

These findings lay the foundation for identifying flow transitions and particle instabilities in viscoelastic suspensions, which will be further explored in upcoming experiments.