63 rd annual dfd meeting of the american physical society long beach, california
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Contact line dynamics of a liquid meniscus advancinginto a microchannel with chemical heterogeneitiesC. Wylock1, M. Pradas2, B. Haut1, P. Colinet1 and S. Kalliadasis2
1 Université Libre de Bruxelles – Transfers, Interfaces and Processes2 Imperial College London – Chemical Engineering Department
63rd Annual DFD Meetingof the American Physical SocietyLong Beach, CaliforniaNovember 21-23, 2010
Motivation Contact line dynamics
• Rapidly growing fields of:─ Microfluidics─ Miniaturisation of chemical devices
• Small length scale solid surface properties become crucial
Page 2
Goal Gas-liquid meniscus moving in a "Hele-Shaw cell like "
microchannel Surface chemically heterogeneous spatial
distribution of wetting properties 2 configurations
Effect of chemical heterogeneities on meniscus dynamics ?
2D configuration 3D configuration
Page 3
Modelling Phase field approach
• f represents the 2 phases• Interface at f=0
Page 4
Modelling Phase field approach
• f represents the 2 phases• Interface at f=0
Equilibrium given by Ginzburg-Landau model
Free energy formulation
Double-well potential
Chemical potential
Page 5
Modelling Phase field approach
• f represents the 2 phases• Interface at f=0
Equilibrium given by Ginzburg-Landau model
Free energy formulation
Double-well potential
Chemical potential
Page 6
Modelling Wetting boundary condition
Conserved dynamic equation
Page 7
Standard deviation s= disorder strength
with[1]
[1] Cahn, J. Chem. Phys. 66 (1977), 3667
Results and discussion 2D configuration
• Typical simulation result
Page 8
Results and discussion 2D configuration
• Typical simulation result• Statistical analysis on several disorder realisations
Page 9
Results and discussion 2D configuration
• Typical simulation result• Statistical analysis on several disorder realisations
Page 10
Results and discussion 2D configuration
• Typical simulation result• Statistical analysis on several disorder realisations
Page 11
Results and discussion 2D configuration
• Typical simulation result• Statistical analysis on several disorder realisations
Page 12
Results and discussion 2D configuration
• Typical simulation result• Statistical analysis on several disorder realisations
Page 13
Chemical disorder contact angle hysteresis enhanced by disorder strength
Results and discussion 3D configuration
• Contact line dynamics: preliminary analysis─ interface width follows fractal dynamics
( scale-invariant growth)
Page 14
Results and discussion 3D configuration
• Contact line dynamics: preliminary analysis─ interface width follows fractal dynamics
( scale-invariant growth)─ pinning-depinning effects and associated avalanche dynamics
Page 15
Avalanche sitePinning site
Results and discussion 3D configuration
• Contact line dynamics: preliminary analysis─ interface width follows fractal dynamics
( scale-invariant growth)─ pinning-depinning effects and associated avalanche dynamics
induced by the chemical disorder
Statistical analysis to perform for various disorder configurations
Page 16
Conclusion and future plans Phase field contact line dynamics in chemically
heterogeneous microchannel Chemical disorder induces
• 2D: hysteresis of contact angle hysteresis “jump” function of disorder strength
• 3D: kinetic roughening process of contact line motion, pinning-depinning effects
Future plans• Statistical analysis for 3D configuration:
─ Characterization of the scaling growth factors ─ Avalanche dynamics
Page 17
18
Modelling Boundary conditions for 2D configuration
Page 19
Modelling Boundary conditions for 3D configuration
Page 20
Results and discussion 2D configuration
• Typical simulation result• Statistical analysis on several disorder realisations
Page 21
Chemical disorder contact angle hysteresis enhanced by disorder strength
Results and discussion 3D configuration
• Typical simulation results
Page 22
Results and discussion 3D configuration
• Typical simulation results• Contact line dynamic: preliminary analysis
─ interface width growth follows fractal dynamic
Page 23
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