Abstract/Details

MicroPIV measurement of turbulent and transitional flow characteristics in microchannels


2005 2005

Other formats: Order a copy

Abstract (summary)

Microscopic particle image velocimetry (microPIV) experiments were performed on smooth and roughened microchannels. These measurements represent the first instantaneous velocity field measurements in a turbulent microscale flow.

The effect of hydraulic diameter on flow through smooth square polydimethylsiloxane (PDMS) microchannels was investigated by varying the hydraulic diameter from 200 μm to 640 μm for Reynolds numbers ranging from 200 through 3971. The data was analyzed to yield mean velocity profiles u, velocity fluctuations (u') and (v'), and Reynolds stresses - ( u'v') and these were compared to experimental data of macroscale channel flow. The microscale and macroscale results agreed quite well, indicating there are no significant differences between microscale and macroscale channel flow.

Next, the effect of aspect ratio on flow through smooth rectangular microchannels was investigated by varying the aspect ratio from 0.97 to 5.69 for Reynolds numbers ranging from 200 through 3267. By analyzing mean velocity profiles u, velocity fluctuations (u') and (v'), and Reynolds stresses---(u'v') and comparing these experimental data with macroscale results, the data were used to clarify the discrepancies on transition in microfluidic flow due to the aspect ratio effect that was observed by previous researchers.

The statistical analysis of spatial correlation coefficients of velocity fluctuations to characterize large scale turbulent structures in these two experiments indicated that the large scale turbulent structures observed in microchannels are similar to their macroscale counterparts.

Flow within roughened microchannels of dimensions 600 μm x 400 μm with one single microstructure measuring 120 μm x 120 μm x 43 μm was studied by analyzing the velocity profiles in the wakes of microstructures. The data were obtained for comparison of the experimental velocities with CFD results at varying downstream locations and depths to provide for the validation of CFD in microfluidic flow study.

Finally, the experiments were performed in the roughened microchannels 600 μm x 400 μm with one single cubic microstructure dimensioning at 20 μm 40 μm and 50 μm for Reynolds number ranging from laminar to turbulent. The data obtained at upstream and various downstream locations and various depths indicated significant turbulence enhancement by introducing man-made surface roughness in microchannels.

Indexing (details)


Subject
Mechanical engineering;
Fluid dynamics;
Gases
Classification
0548: Mechanical engineering
0759: Fluid dynamics
0759: Gases
Identifier / keyword
Applied sciences; Pure sciences; MicroPIV; Microchannels; Transitional flow; Turbulent flows
Title
MicroPIV measurement of turbulent and transitional flow characteristics in microchannels
Author
Li, Hao
Number of pages
166
Publication year
2005
Degree date
2005
School code
0097
Source
DAI-B 67/01, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
0542477777, 9780542477775
Advisor
Olsen, Michael G.
University/institution
Iowa State University
University location
United States -- Iowa
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3200439
ProQuest document ID
304990906
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/304990906
Access the complete full text

You can get the full text of this document if it is part of your institution's ProQuest subscription.

Try one of the following:

  • Connect to ProQuest through your library network and search for the document from there.
  • Request the document from your library.
  • Go to the ProQuest login page and enter a ProQuest or My Research username / password.