Inertial lift on a particle in a straight microchannel of Newtonian, power-law and Carreau-Yasuda fluids: A simulation study toward optimized particle separation

• Published in: Journal of non-Newtonian fluid mechanics 2023-02, Vol.312, p.104977, Article 104977
• Main Authors: Jannesari Ghomsheh, Mehryar, Jafari, Azadeh, Funfschilling, Denis
• Format: Article
• Language: English
• Subjects: Carreau-Yasuda model; Engineering Sciences; Inertial lift forces; Inertial microfluidics; Newtonian fluid; Particle separation; Power-law model
• ISSN: 0377-0257; 1873-2631
• DOI: 10.1016/j.jnnfm.2022.104977

•3D DNS of inertial lift forces on a particle in a straight rectangular microchannel.•Shear gradient and wall-induced lift in Newtonian fluids and xanthan gum solutions.•Variable viscosity for controlling the particle migration in different Re numbers.•Inconsistent lift and equilibrium position in power-law and Carreau-Yasuda models.•Shear-thinning viscosity pushes the equilibrium positions to the microchannel walls. Direct three-dimensional Numerical Simulations (DNS) are performed to calculate the inertial lift forces on a single particle in a straight rectangular microchannel of Newtonian fluid and xanthan gum solutions. The shear-thinning behavior of xanthan gum solutions is demonstrated experimentally and represented mathematically using the power-law and Carreau-Yasuda models. Similar to Newtonian fluids, our simulations delineate the dominant region of shear gradient and wall-induced lift forces for power-law and Carreau-Yasuda fluids. The variable viscosity of non-Newtonian fluids allows us to better control the particle motion which seems promising in the inertial focusing method. Owing to their different formulations, power-law and Carreau-Yasuda models result in inconsistent lift forces. This incompatibility appears to intensify at higher concentrations of xanthan gum (higher shear-thinning characteristics) solutions and stems from the fact that the power-law viscosity considerably diverges from the experimental and Carreau-Yasuda viscosity in both low and high shear-rate regions. The power-law model is more sensitive to the Re number compared to the Carreau-Yasuda model, especially for high concentrations of xanthan gum solutions. Furthermore, the results indicate the presence of two equilibrium positions for both Newtonian fluid and xanthan gum solutions in the microchannel cross-section. By increasing the Re number, the Newtonian and Carreau-Yasuda fluids push the particle equilibrium positions toward the center of the microchannel while the power-law model pushes the equilibrium positions toward the microchannel wall. Furthermore, both power-law and Carreau-Yasuda models indicate the shift of equilibrium positions to the microchannel wall by increasing the shear-thinning characteristics.