Experimental investigation of a scaled-up passive micromixer with uneven interdigital inlet and teardrop obstruction elements

Kristina J. Cook, Yanfeng Fan, Ibrahim Hassan

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Micromixers are vital components in micro total analysis systems. It is desirable to develop micromixers which are capable of rapidly mixing two or more fluids in a small footprint area, while minimizing mechanical losses. A novel planar scaled-up passive micromixer is experimentally investigated in this study. The design incorporates a 7-substream uneven interdigital inlet which supplies two liquid species in a parallel arrangement and promotes diffusion along the side walls. Forty-eight staggered teardrop-shaped obstruction elements located along the channel length combined with 32 side walls protrusions increase the two-fluid interfacial area while converging the flow due to periodic reductions in crosssectional area. The scaled-up micromixer has a mixing channel length of 110 mm with a mixing channel height and width of 2 and 5 mm, respectively. Experimental investigations are carried out at four locations along the channel length and at Reynolds numbers equal to 1, 5, 10, 25, 50, and 100, where the Reynolds number is calculated based on total two-fluid flow and the mixing channel hydraulic diameter. Flow visualization is employed to study flow patterns, while induced fluorescence (IF), using de-ionized water and low concentration Rhodamine 6G solutions, provides mixing efficiency data. Results show a change in dominant mixing mechanism from mass diffusion to mass advection, with a critical Reynolds number of 25. At high Reynolds numbers, the formation of additional lamellae is observed, as is the formation of Dean vortices in the vicinity of the teardrop obstructions. Of the tested cases, the highest outlet mixing efficiency, 68.5%, is achieved at a Reynolds number of 1, where mass diffusion dominates. At low Reynolds numbers, superior mixing efficiency is due primarily to the implementation of the uneven interdigital inlet. A comparable mixing length is proposed to allow for reasonable comparison with published studies.

Original languageEnglish
Pages (from-to)1261-1275
Number of pages15
JournalExperiments in Fluids
Volume52
Issue number5
DOIs
Publication statusPublished - May 2012
Externally publishedYes

Fingerprint

Reynolds number
Fluids
fluids
flow visualization
high Reynolds number
systems analysis
Advection
low Reynolds number
footprints
lamella
Flow visualization
outlets
rhodamine
advection
hydraulics
Flow patterns
fluid flow
Flow of fluids
low concentrations
flow distribution

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Fluid Flow and Transfer Processes
  • Computational Mechanics
  • Mechanics of Materials

Cite this

Experimental investigation of a scaled-up passive micromixer with uneven interdigital inlet and teardrop obstruction elements. / Cook, Kristina J.; Fan, Yanfeng; Hassan, Ibrahim.

In: Experiments in Fluids, Vol. 52, No. 5, 05.2012, p. 1261-1275.

Research output: Contribution to journalArticle

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