Numerical Investigation of Multistage Viscous Micropump Configurations

Abstract

The viscous micropump consists of a cylinder placed eccentrically inside a microchannel, where the rotor axis is perpendicular to the channel axis. When the cylinder rotates, a net force is transferred to the fluid because of the unequal shear stresses on the upper and lower surfaces of the rotor. Consequently, this causes the surrounding fluid in the channel to displace toward the microchannel outlet. The simplicity of the viscous micropump renders it ideal for micropumping; however, previous studies have shown that its performance is still less than what is required for various applications. The performance of the viscous micropump, in terms of flow rate and pressure capabilities, may be enhanced by implementing more than one rotor into the configuration either horizontally or vertically oriented relative to each other. This is analogous to connecting multiple pumps in parallel or in series. The present study will numerically investigate the performance of various configurations of the viscous micropumps with multiple rotors, namely, the dual-horizontal rotor, triple-horizontal rotor, symmetrical dual-vertical rotor, and eight-shaped dual-vertical rotor. The development of drag-and-lift forces with time, as well as the viscous resisting torque on the cylinders were studied. In addition, the corresponding drag, lift, and moment coefficients were calculated. The flow pattern and pressure distribution on the cylinders’ surfaces are also included in the study. Results show that the symmetrical dual-vertical rotor configuration yields the best efficiency and generates the highest flow rate. The steady-state performance of the single-stage micropump was compared to the available experimental and numerical data and found to be in very good agreement. This work provides a foundation for future research on the subject of fluid phenomena in viscous micropumps.

Optimal theoretical design of 2-D microscale viscous pumps for maximum mass flow rate and minimum power consumption

“…After its introduction in 1996, the viscous micropump has been the subject of a stream of publications including (Sharatchandra et al, 1997(Sharatchandra et al, , 1998DeCourtye et al, 1998;Abdelgawad et al, 2004Abdelgawad et al, , 2005Gad-el-Hak, 1999;Blanchard et al, 2004. These authors examined various design features and fundamentals issues associated with such micropumps, including the effects of channel height, rotor eccentricity and angular velocity on the pump performance (Sen et al, 1996), slip velocity (Sharatchandra et al, 1997), thermal effects (Sharatchandra et al, 1998), transient effects (Abdelgawad et al, 2004), and multistage configurations (Abdelgawad et al, 2005). Yet none of these previous reports have considered the optimization of the mass flow constrained to shaft power consumption, which is a key factor in the design of efficient micropumps.…”

Piezoelectric diffuser/nozzle micropump with double pump chambers

“…Stemme proposed the first pump with diffuser/nozzle structures in 1993 [2]. During the past thirty years, different embodiments of micropumps have emerged endlessly [3][4][5]. The valveless diffuser/nozzle pump using the diffuser/nozzle instead of valves for floe rectification is the classical valveless micropump.…”

Microscale disk-induced gas displacement with and without slip

“…Such micropumps and micro-gas-displacement devices satisfy the need to circulate or move fluid through macroscale and/or microscale channels in many applications including microsensors, separation devices, drug delivery systems, electronics cooling and other small-scale and microscale fluidic devices. Many different micropumps are proposed to meet this need, generally to fulfill specific applications [11][12][13][14][15]. These include membrane pumps (both without check valves and with check valves), electrohydrodynamic (EHD) pumps, electrokinetic (EK) pumps, viscous pumps [11,12], rotary pumps [13], peristaltic pumps, ultrasonic pumps, to name some of the more common types.…”

“…Recently developed examples are described by Kilani et al [14], who describe the influences of the channel aspect ratio on pressure rise and flow characteristics of spiral-channel viscous micropumps, and Abdelgawad et al [15], who present numerically determined characteristics, such as flow rate, velocity, streamlines, shear stress and efficiency, as they result from the use of multi-rotors placed inside of flow passages.…”