Contact line dynamics of a liquid meniscus advancing into a microchannel with chemical heterogeneities C. Wylock 1, M. Pradas 2, B. Haut 1, P. Colinet 1 and S. Kalliadasis 2 1 Universit Libre de Bruxelles Transfers, Interfaces and Processes 2 Imperial College London Chemical Engineering Department 63 rd Annual DFD Meeting of the American Physical Society Long Beach, California November 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 represents the 2 phases Interface at =0 Page 4 Modelling Phase field approach represents the 2 phases Interface at =0 Equilibrium given by Ginzburg-Landau model Free energy formulation Double-well potential Chemical potential Page 5 Modelling Phase field approach represents the 2 phases Interface at =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 = 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 site Pinning 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