63 rd annual dfd meeting of the american physical society long beach, california

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

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

Modelling Phase field approach

• f represents the 2 phases• Interface at f=0

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

Modelling Wetting boundary condition

Conserved dynamic equation

Standard deviation s= disorder strength

with[1]

[1] Cahn, J. Chem. Phys. 66 (1977), 3667

Results and discussion 2D configuration

• Typical simulation result


• Typical simulation result• Statistical analysis on several disorder realisations



Chemical disorder contact angle hysteresis enhanced by disorder strength


• Contact line dynamics: preliminary analysis─ interface width follows fractal dynamics

( scale-invariant growth)



( scale-invariant growth)─ pinning-depinning effects and associated avalanche dynamics

Avalanche sitePinning site



( scale-invariant growth)─ pinning-depinning effects and associated avalanche dynamics

induced by the chemical disorder

Statistical analysis to perform for various disorder configurations

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

Modelling Boundary conditions for 2D configuration

Modelling Boundary conditions for 3D configuration



Chemical disorder contact angle hysteresis enhanced by disorder strength


• Typical simulation results


• Typical simulation results• Contact line dynamic: preliminary analysis

─ interface width growth follows fractal dynamic

63 rd annual dfd meeting of the american physical society long beach, california

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