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

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


Hyeong Yong Song

Seung Hak Lee

Reza Salehiyan

Kyu Hyun


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.


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.

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
Keywords Particle focusing, Dimensionless numbers, Shear thinning, Microfluidics, Viscoelasticity