UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

Vortex induced transport phenomena in flows past micropins

Zhang, S; Cagney, N; Balabani, S; Tiwari, MK; (2018) Vortex induced transport phenomena in flows past micropins. In: Proceedings of the 16th International Heat Transfer Conference. (pp. pp. 8926-8933). IHTC: Beijing, China. Green open access

[img]
Preview
Text
IHTC-full paper_SZ_et_al_Revised.pdf - Accepted version

Download (3MB) | Preview

Abstract

The potential of vortex shedding behind cylindrical micropins to enhance mixing at the microscale is investigated. The confinement present in microchannels may prevent or delay the formation of vortices and weaken the performance of such a passive micromixer. Thus, the onset of vortex shedding in confined flows in micromixers need be elucidated to optimize mixing performance. In this work, the flow past a single cylindrical pin in microchannels with different levels of confinement was studied experimentally using a custom high-speed micro particle-image velocimetry (µPIV) system. This system can resolve the instantaneous velocity fields and the corresponding vortex shedding frequencies. Results show that the onset of vortex shedding is delayed by enhancing the vertical confinement for a channel width of three pin diameters. However, when vortex shedding is present, the vortex shedding frequency and corresponding Strouhal numbers (St) are greater in more confined channels for the same Reynolds number (Re). Finite-Time Lyapunov Exponent (FTLE) analysis was performed on the acquired velocity fields to estimate the mixing performance. Preliminary results with a channel three pin diameters wide and three pin diameters high indicated that vortex shedding induces an enhancement in both the mixing in the wake and the mass flux across the centreline of the wake. We also discuss our results in the context of prior works focussing on exploiting vortex shedding for enhancing thermal transport.

Type: Proceedings paper
Title: Vortex induced transport phenomena in flows past micropins
Event: 16th International Heat Transfer Conference
Open access status: An open access version is available from UCL Discovery
DOI: 10.1615/IHTC16.tpm.024061
Publisher version: https://doi.org/10.1615/IHTC16.tpm.024061
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Nano/Micro scale measurements, Micromixing, Vortex shedding, High speed µPIV, FTLE
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/10078514
Downloads since deposit
33Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item