Effect of Fluid Viscosity on the Deposition of Colloidal Particles in an Expansion-Contraction Microchannel Flow

Abstract

Particle deposition, occurring during the transport of colloidal suspension through process streams, can degrade the processing performance by increasing pressure drop and inducing channel clogging. In this study, we examine the particle deposition phenomena in an expansion-contraction microchannel visualize by a microfluidic observation system. Image processing techniques are employed to analyze the effect of fluid viscosity qualitatively and quantitatively on the deposition phenomena in both Newtonian and non-Newtonian fluids. Glycerin aqueous solution and poly (ethylene oxide) (PEO) solution are utilized as the Newtonian and non-Newtonian fluid, respectively, with viscosity manipulated by changing the concentration of glycerin as a thickening agent. Polystyrene (PS) latex particles are suspended in each medium and flows through the expansion-contraction microchannel. Particles deposit more readily in the downstream region compared to the cavity region for both Newtonian and non-Newtonian fluids. As fluid viscosity increases, the quantity of deposited particles decreases in both media. Notably, particle deposition in the non-Newtonian fluid occurs more extensively in the cavity region due to the fluctuating flow behavior and particle-polymer interactions.