Performance enhancement of double-rotor viscous micropump for transporting Bingham fluid

Abstract

Rotary viscous micropumps, recognized as a prevalent mechanism in microfluidics systems, have recently been introduced to transport non-Newtonian fluids, especially yield-stress fluids. However, conventional single-rotor viscous micropumps often lack efficiency and effectiveness when dealing with these particular fluid types. To address this challenge, the present study explores the use of dual-rotor viscous micropumps for transporting Bingham fluids and their associated performance enhancement for the first time. In a four-step approach, the effects of geometrical and operational parameters, including diameter ratio, distance ratio, rotational velocity ratio, and height ratio on two performance metrics, flow rate, and efficiency, are analyzed, and optimal values are recorded. Enhanced designs, optimized for maximum flow rate and efficiency, are evaluated at four distinct Bingham numbers (Bn), with comparative performance assessments against single-rotor micropumps. The working fluid is simulated using the Herschel-Bulkley model to capture its non-Newtonian behavior, with velocity and viscosity contours providing insights into flow characteristics. Numerical findings reveal significant performance improvements with dual-rotor micropumps, achieving a maximum enhancement rate of 12 while Bn = 2 compared to single-rotor configurations. Additionally, the adverse effects of yield stress on both efficiency and flow rate are substantially mitigated, particularly for high-viscosity fluids, due to a reduction in blocking vortex structures. These findings highlight the potential of dual-rotor viscous micropumps as an effective solution for transporting yield-stress fluids.