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娜顿郎
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1 微流體模擬與計算 Numerical Simulation of Microfluidic Applications Shiu-Wu Chau ( 趙修武 ) Department of Mechanical Engineering Chung Yuan Christian University chausw@cycu.edu.tw

2 1 Motivations Microfluidic phenomena appear in many scientific and engineering applications, such as Bio- and 3C products. Micro-Array (Elisa) Portable DMFC (Toshiba) Micromixer () OLED Display (Samsung)

3 2 Impinging Behaviors of Droplet-Film Interaction Acknowledgements: Prof. A.B. Wang (NTU)

4 3 Droplet Impingement is closely related to Spray coating and drying Bio-chip technology for Bio-Engineering - dosing and cleaning in biomedical system (e.g:elisa)

5 4 Graphical Comparison between Experimental and Numerical Results t=0.1ms t=0.5ms t=2.0ms t=7.5ms

6 5 Histogram of Free Surface Profiles t=0.1ms t=0.5ms t=1.0ms t=2.5ms t=5.0ms t=7.5ms t=10.0ms t=12.5ms t=15.0ms H * = H D

7 6 Capillary Driven Microchannel Flow Acknowledgements: Prof. A.B. Wang (NTU)

8 7 No. of Channels 7 Histogram of Capillary Front 5 3 1

9 8 Histogram of Capillary Front

10 9 Inkjet Printing Applications Acknowledgements: Prof. T.M. Liou (NTHU)

plate Ink Manifold Diaphragm Piezoelectric transducer Ink

11 10 Precision inkjet printing is employed in P-OLED/LEP Panels LCD Manufacturing Printed Electronics Biosensors Orifice plate Ink Manifold Diaphragm Piezoelectric transducer Ink droplet Ink Channel Rigid Shell Acoustic Pulse

12 11 Fluid Front inside Nozzle Meinhart and Zhang (MicroPIV) Velocity Inconsistence Velocity Inconsistence Velocity Inconsistence 1.409

13 12 Schematic Illustration of Deposition Process PLED Display for Cell Phone 2 x 3 cm, 60 x 90 pixels PPV PANI ITO layers under 0.1 um thick Resist 110 um Pixel 220 um Monochrome Display Layout Pixels 75 um Resist 35 um Color Display Layout

14 13 Influence of Impingement Velocity on Droplet Meniscus (at small velocity) (at large velocity)

15 14 Influence of Contact Angle on Droplet Meniscus

16 15 Prediction of Mixing Efficiency In a Micromixer Acknowledgements: Prof. M. Chang (CYCU) and Prof. Y.H. Hu (NIT)

17 16 Fluid Mixing in a Micromixer Measurement Original Gray Level Efficiency Flux=14.45 μl/s Simulation h = 10 μm 50 μm 100 μm 150 μm 190 μm Flux=14.45 μl/s Flux=14.45 μl/s

18 17 Fluid Mixing in a Micromixer Exp.1: Physical Reaction (Red and Green Dyes) Mixing Efficiency versus Flow rate E r ( % ) E r ( % ) Exp.2: Chemical Reaction (Red Indicator and Sodium Hydroxide) Exp μl/s Num μl/s Exp μl/s Num μl/s Exp μl/s Num μl/s r ( μm ) Exp. D = 6 x 10-6 D = 4 x 10-6 D = 2 x 10-6 D = 10-6 D = 0 Q = μl/s r ( μm ) E ( % ) 100 D= D= Exp. 1 Exp. 2 D = 6 x 10-6 D = 4 x 10-6 D = 2 x 10-6 D = 10-6 D = Q ( μl / s) E = f ( Q ) = a + bq + cq 2

19 Acknowledgements: Prof. A.B. Wang (NTU) 18 Mathematical Modeling And Numerical Scheme

20 19 Governing Equations in Integration Form (1) Velocity and Pressure Coupling in Flow Field Continuity Equation t t ρdv + ρ( v n)ds = V S Momentum Equation ρvdv + ρv( v n)ds = ( f n)ds+ V Stress Tensor u u i j f i = μ + e j + pei + x j x i S f σ i 0 S V ρbdv

21 20 Governing Equations in Integration Form (2) Flows with Front Front Transport Equation t ρcdv + ρc( v n)ds = ( q V Fick s Law (Diffusion Effects) q v = ρd c S S n)ds Continuum Force Model (Capillary Effects) f σ = σ c c c

22 21 Numerical Schemes Second-Order Finite Volume Discretization Non-Staggered Cell Node Arrangement Primary Variable Approach SIMPLE Algorithm to decouple pressure and velocity Segregated Solution Procedure VOF-based Front Capturing Approach HRIC Scheme to Capture Front Location

23 22 Concluding Remarks 1. Numerical simulation of microfluidic problems related to engineering applications has been conducted in a macroscopic way, i.e. in a continuum approach. 2. The proposed numerical scheme seems to be very promising in modeling microfluidic flows with moving front, which can provide important information for engineering applications. 3. Further understanding of microfluidic characteristics is demanded for the design and analysis of microfluidic systems. 4. The techniques of multi-scale modeling is a necessity for advanced microfluidic simulations.

24 23 Questions and Comments Thank You for Your Attention

CFDesign 2 1 CFDesign CFDesign CAD ~ r /min mm 1

CFDesign 2 1 CFDesign CFDesign CAD ~ r /min mm 1 33 3 Vol 33 No 3 2012 6 Journal of Jinan University Natural Science Jun 2012 1 2 2 1 2 528436 CFDesign CFDesign TQ430 6 + 64 A 1000-9965 2012 03-0316 - 07 Numerical simulation for gas and liquid particles