Flow transport in a microchannel induced by moving wall contractions: a novel micropumping mechanism

Abstract

A novel micropumping mechanism based on a theoretical model that describes flow transport in a microchannel induced by moving wall contractions in the low Reynolds number flow regime is presented. The channel is assumed to have a length that is much greater than its width (δ = W/L 1) and the upper wall is subjected to prescribed, non-peristaltic, localized moving contractions. Lubrication theory for incompressible viscous flow at low Reynolds number (R e ∼ δ) is used to model the problem mathematically and to derive expressions for the velocity components, pressure gradient, wall shear stress, and net flow produced by the wall contractions. The effect of contraction parameters such as amplitude and phase lag on the time-averaged net flow over a single cycle of wall motions is studied. The results presented here are supported by passive particle tracking simulations to investigate the possibility of using this system as a pumping mechanism. The present study is motivated by collapse mechanisms observed in entomological physiological systems that use multiple contractions to transport fluid, and the emerging novel microfluidic devices that mimic these systems.

Insect-Inspired Micropump: Flow in a Tube with Local Contractions

“…A solution to the above linear system problem can be found by either collocating the Stokeslets sources at an optimal distance away from the domain boundaries as proposed by [24] or by using regularized Stokeslets expressions as derived by [21]. Alternatively, similar results are accomplished by introducing a regularization to the matrix A itself [1]; this approach has been shown to provide an efficient and fast converging of the features when solving the linear system. Figure 1.…”

“…Figure 1. Problem schematic given to mimic the insect's main tracheal tube segment with two contractions [1] and the Stokeslets-mesh-free numerical setup: (a) 3D tube with moving upper wall contraction profile R(z, t); (b) g 1 (t) and g 2 (t), the motion protocols assigned to the first and second contractions, respectively.…”

“…In this paper, we follow the algorithm given in [1] to solve for the Stokeslets strengths and to reconstruct the flow field in a 3D tube subjected to localized wall contractions that move according to a specific wall profile, as shown in Figure 1b. More details about implementing the Stokeslets-mesh-free method can be found in [2].…”

“…These microstructures can be then used as components in functional micromachines, such as pumps, valves and separators, where all of these components can be built and assembled on a single chip. Here, we focus our attention on a novel micropumping paradigm that is inspired by insect respiration physiology [1][2][3][4][5][6][7][8][9].…”

“…In this study, we extend our bioinspired micropumping models [1][2][3][4][5][6][7][8] to simulate the flow transport in a tubular geometry. In particular, we present a three-dimensional numerical simulation based on the regularized Stokeslets method of fundamental solutions (MFS) to study flow motions within an insect tracheal-like tube.…”