Inertial instabilities in a microfluidic mixing-separating device



Domingues, Allysson F, Poole, Robert J and Dennis, David JC
(2019) Inertial instabilities in a microfluidic mixing-separating device. PHYSICS OF FLUIDS, 31 (7). 074101-.

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Abstract

<jats:p>Combining and separating fluid streams at the microscale has many scientific, industrial, and medical applications. This numerical and experimental study explores inertial instabilities in so-called mixing-separating micro-geometries. The geometry consists of two straight square parallel channels with flow from opposite directions and a central gap that allows the streams to interact, mix, or remain separate (often also referred to as the H-geometry). Under creeping-flow conditions (the Reynolds number tending to zero), the flow is steady, two-dimensional, and produces a sharp interface between fluid streams entering the geometry from opposite directions. When Re exceeds a critical value, one of two different supercritical, inertial instabilities appears which leads to significant changes in the flow pattern and an increased level of interaction between the two streams, although the flow remains steady. The exact form of the instability is dependent on the gap size and the Reynolds number, and we identify two distinct instabilities, one of which appears in devices with large gaps and another which appears in devices with small gaps. At intermediate gap sizes, both instabilities can occur in the same device (at different onset Re). The experimental results for one gap size are used to validate our numerical method, which is then applied to a wider range of gap sizes. The results suggest that the gap size is of primary importance in determining the type of instability that occurs. With a judicious choice of gap size, the instabilities can be exploited (or avoided) in scientific, medical, or other microfluidic applications.</jats:p>

Item Type: Article
Uncontrolled Keywords: 4012 Fluid Mechanics and Thermal Engineering, 40 Engineering
Depositing User: Symplectic Admin
Date Deposited: 25 Jul 2019 13:49
Last Modified: 21 Jun 2024 04:00
DOI: 10.1063/1.5108885
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3050317