Mixing in a Two-stream Microchannel Flow

Yi-Kuen Lee†, Chang Shih‡

Patrick Tabling†, Chih-Ming Ho† 

†Mechanical and Aerospace Engineering Department

University of California, Los Angeles

‡ Department of Mechanical Engineering

Florida State University

APS 99

Outlines

• Objective

• Fabrication & Testing Setup

• Static Source and Sink

• Periodic Source and Sink Mixing

• Conclusion

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Objective

• Mixing in microfluidic devices is an essential process

in bio-medical devices

• Viscous effect dominating in micro channel flow

- Turbulent mixing not possible

• Chaotic mixing found in perfect fluid in a

pulsed source and sink system (Jones and Aref, 1988)

• Apply periodic perturbations in 2-stream micro channel

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Fabrication Processes

Micromixing Device

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Experimental Setup

Microscope & CCD

Digital Syringe Pumps

Micromixing Device

Downstream

Reservoir

High Pressure

Source

Low Pressure

Source

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Steady Microchannel Flow Re=8

d =400?m

L = 11,500 ? m, L/d = 30

v = 18,000 mm/sec

DI water + Rhodamine 6G dye

DI water

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Steady Sink

Sink direction, 26 mm/s

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Periodic Sink

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Re = 4

Re = 2

Re = 3

Re = 6

Re = 11

Re = 38

Re = 57

Steady Sink

10 mm/s

4 mm/s

7 mm/s

13 mm/s

26 mm/s

87 mm/s

130 mm/s

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Steady Source

Re = 2

Re = 8

Re = 15

Re = 28

Re = 38

Re =57

4 mm/s

8 mm/s

15 mm/s

28 mm/s

87 mm/s

130 mm/s

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Periodic Sink T = 14 sec

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Periodic Sink T = 1.82 sec

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Periodic Source T = 6.8 sec

0

T/4

T-/2

T+/2

3T/4

T

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Periodic Source T = 1.3 sec

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Periodic sink at fd/v=1

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Periodic sink at fd/v=1

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Simulation of 4 Particles Trajectories for Different

Strength of Periodic Source and Sink

No mixing

Flow Direction

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Conclusions

• Mixing found in Re~1 flow with periodic perturbation

• A critical frequency occurs at fd/V = 1

• In sink flow, 90o turn of the flow was observed