Relationship between particle focusing and dimensionless numbers in elasto-inertial focusing

Song, Hyeong Yong; Lee, Seung Hak; Salehiyan, Reza; Hyun, Kyu

Abstract

We performed particle focusing in viscoelastic fluids in a straight square microchannel based on elasto-inertial focusing. Probability distribution functions (PDFs) were obtained at various flow rates (40–320 μl/h) for a broad range of medium viscoelasticity (PEO solutions) from a dilute regime (0.01–0.2 wt%) to a semi-dilute regime (0.3–1.0 wt%). To evaluate focusing efficiency, PDF values at the centerline of the microchannel were plotted as a function of three dimensionless numbers: Reynolds number (Re), Weissenberg number (Wi), and elasticity number (El). Relaxation times were carefully calculated by using two different methods for each regime of medium to calculate Wi accurately. As a result, PDF at the centerline as a function of Re and El did not display any scaling tendency, but a single master curve was obtained in the plot of PDF at the centerline as a function of Wi, indicating that Wi is a more suitable parameter for manipulating elasto-inertial focusing than Re or El. In the plot of PDF versus Wi, particle focusing could be divided into two regimes at Wi = 3.16, where maximum PDF was observed. In the first regime (Wi < 3.16), particle focusing increased rapidly with increasing Wi. However, in the second regime (Wi > 3.16), particle focusing was no greater, but scattering increased with increasing Wi due to the shear thinning effect of suspending medium.

Citation

Song, H. Y., Lee, S. H., Salehiyan, R., & Hyun, K. (2016). Relationship between particle focusing and dimensionless numbers in elasto-inertial focusing. Rheologica Acta, 55(11), 889-900. https://doi.org/10.1007/s00397-016-0962-3

• Journal Article Type: Article
• Acceptance Date: Sep 1, 2016
• Online Publication Date: Sep 19, 2016
• Publication Date: 2016-12
• Deposit Date: Jan 30, 2023
• Journal: Rheologica Acta
• Print ISSN: 0035-4511
• Publisher: Springer
• Peer Reviewed: Peer Reviewed
• Volume: 55
• Issue: 11
• Pages: 889-900
• DOI: https://doi.org/10.1007/s00397-016-0962-3
• Keywords: Particle focusing, Dimensionless numbers, Shear thinning, Microfluidics, Viscoelasticity