Heat transfer enhancement in a cross-slot micro-geometry

Abed, Waleed M, Domingues, Allysson F ORCID: 0000-0003-2071-6738, Poole, Robert J ORCID: 0000-0001-6686-4301 and Dennis, David JC ORCID: 0000-0003-0214-7885
(2017) Heat transfer enhancement in a cross-slot micro-geometry. INTERNATIONAL JOURNAL OF THERMAL SCIENCES, 121. pp. 249-265.

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The cross-slot is a common geometric shape in microfluidic applications. In this article we investigate the influence of a purely-inertial flow instability on the enhancement of heat transfer in a cross-slot micro-geometry where symmetry is broken but the flow remains steady. The cross-slot comprises two crossed square channels with opposed inlets and outlets, which generate a stagnation point at the geometric centre (when the flow remains stable and symmetric). In the experiments, Rhodamine-B is utilised as a temperature-sensitive dye to measure the temperature distribution, these results compare well with three-dimensional numerical simulations, which are used to further elucidate the flow behaviour and heat transfer characteristics. The flow of a Newtonian fluid is steady, two-dimensional and produces a sharp symmetric boundary between fluid streams entering the cross-slot from opposite directions at low Reynolds numbers (Re). Therefore, only conduction heat transfer occurs between the fluid streams as there is virtually no mixing between them. Beyond a certain critical value of Re, approximately 40, a steady symmetry-breaking bifurcation occurs and convective heat transfer arises because an axially oriented spiral vortex is created in the outlet arms. The effects of this purely-inertial instability suggest it is an effective method of enhancing mixing and heat transfer in microfluidic devices that can be exploited in applications such as lab-on-chip and micro chemical-reaction devices at relatively low Reynolds numbers (i.e. Re < 100).

Item Type: Article
Uncontrolled Keywords: Cross-slot, Micro-geometry, Heat transfer, Steady symmetry-breaking bifurcation, Spiral vortex, Hysteresis
Depositing User: Symplectic Admin
Date Deposited: 20 Jul 2017 10:54
Last Modified: 19 Jan 2023 06:58
DOI: 10.1016/j.ijthermalsci.2017.07.017
Open Access URL: http://www.sciencedirect.com/science/article/pii/S...
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3008546