1. J.E. Sprittles (University of Birmingham / Oxford, U.K.) Y.D. Shikhmurzaev(University of Birmingham, U.K.) Seminar at KAUST, February 2012

2. ‘Impact’ A few years after completing my PhD.....

3. Wetting: Statics Non-Wettable (Hydrophobic) Wettable (Hydrophilic)

4. Wetting: Dynamics

5. Wetting: As a Microscopic Process Macroscale Microscale Meniscus Capillary tube Wetting front

6. Wetting: Micro-Macro Spreading on a Porous Medium

8. Capillary Rise 50nm x 900nm Channels Han et al 06 27mm Radius Tube Stange et al 03 1 Million Orders of Magnitude!!

9. Curtain Coating

10. Curtain Coating Optimization Increased Coating Speed

11. Harnessing Instabilities: Spinning Disk Atomizer

12. Polymer-Organic LED (P-OLED) Displays

13. Inkjet Printing of P-OLED Displays Microdrop Impact & Spreading

14. Additive Manufacturing

16. Why bother? 1 - Recover Hidden Information 2 - Map Regimes of Spreading 3 – Experiment Millimetres in Milliseconds - Rioboo et al (2002) Microns in Microseconds - Dong et al (2002)

17. Wetting: Statics ) Young Laplace Contact Line Contact Angle

18. Wetting: Statics

19. ) Dynamics: Classical Modelling Incompressible Navier Stokes Stress balance Kinematic condition No-Slip Impermeability Angle Prescribed No Solution!

20. L.E.Scriven (1971), C.Huh (1971), A.W.Neumann (1971), S.H. Davis (1974), E.B.Dussan (1974), E.Ruckenstein (1974), A.M.Schwartz (1975), M.N.Esmail (1975), L.M.Hocking (1976), O.V.Voinov (1976), C.A.Miller (1976), P.Neogi (1976), S.G.Mason (1977), H.P.Greenspan (1978), F.Y.Kafka (1979), L.Tanner (1979), J.Lowndes (1980), D.J. Benney (1980), W.J.Timson (1980), C.G.Ngan (1982), G.F.Telezke (1982), L.M.Pismen (1982), A.Nir (1982), V.V.Pukhnachev (1982), V.A.Solonnikov (1982), P.-G. de Gennes (1983), V.M.Starov (1983), P.Bach (1985), O.Hassager (1985), K.M.Jansons (1985), R.G.Cox (1986), R.Léger (1986), D.Kröner (1987), J.-F.Joanny (1987), J.N.Tilton (1988), P.A.Durbin (1989), C.Baiocchi (1990), P.Sheng (1990), M.Zhou (1990), W.Boender (1991), A.K.Chesters (1991), A.J.J. van der Zanden (1991), P.J.Haley (1991), M.J.Miksis (1991), D.Li (1991), J.C.Slattery (1991), G.M.Homsy (1991), P.Ehrhard (1991), Y.D.Shikhmurzaev (1991), F.Brochard-Wyart (1992), M.P.Brenner (1993), A.Bertozzi (1993), D.Anderson (1993), R.A.Hayes (1993), L.W.Schwartz (1994), H.-C.Chang (1994), J.R.A.Pearson (1995), M.K.Smith (1995), R.J.Braun (1995), D.Finlow (1996), A.Bose (1996), S.G.Bankoff (1996), I.B.Bazhlekov (1996), P.Seppecher (1996), E.Ramé (1997), R.Chebbi (1997), R.Schunk (1999), N.G.Hadjconstantinou (1999), H.Gouin (10999), Y.Pomeau (1999), P.Bourgin (1999), M.C.T.Wilson (2000), D.Jacqmin (2000), J.A.Diez (2001), M.&Y.Renardy (2001), L.Kondic (2001), L.W.Fan (2001), Y.X.Gao (2001), R.Golestanian (2001), E.Raphael (2001), A.O’Rear (2002), K.B.Glasner (2003), X.D.Wang (2003), J.Eggers (2004), V.S.Ajaev (2005), C.A.Phan (2005), P.D.M.Spelt (2005), J.Monnier (2006) ‘Moving Contact Line Problem’

21. r Pasandideh-Fard et al 1996 Dynamic Contact Angle Required as a boundary condition for the free surface shape. r t

22. Speed-Angle Formulae R σ1σ1 σ 3 - σ 2 Young Equation Dynamic Contact Angle Formula ) U Assumption: A unique angle for each speed

23. Capillary Rise Experiments

25. Physics of Dynamic Wetting Make a dry solid wet. Create a new/fresh liquid-solid interface. Class of flows with forming interfaces. Forming interface Formed interface Liquid-solidinterface Solid

26. Relevance of the Young Equation R σ 1e σ 3e - σ 2e Dynamic contact angle results from dynamic surface tensions. The angle is now determined by the flow field. Slip created by surface tension gradients (Marangoni effect) θeθe θdθd Static situationDynamic wetting σ1σ1 σ 3 - σ 2 R

27. In the bulk: On liquid-solid interfaces: At contact lines: On free surfaces: Interface Formation Model θdθd e2e2 e1e1 n n f (r, t )=0 Interface Formation Modelling

28. Comparison With Experiments Perfect wetting (Hoffman 1975; Ström et al. 1990; Fermigier & Jenffer 1991) Partial wetting (□: Hoffman 1975;  : Burley & Kennedy 1976; ,,  : Ström et al. 1990) The theory is in good agreement with all experimental data published in the literature.

30. Graded Mesh – For Both Models

31. Arbitrary Lagrangian-Eulerian (Free surface nodes follow the fluid’s path; bulk’s don’t)

32. Oscillating Drops: Code Validation For Re=100, f2 = 0.9

33. Oscillating Drops: Code Validation a b

35. Impact at Different Scales Millimetre Drop Microdrop Nanodrop

36. Pyramidal (mm-sized) Drops Experiment Renardy et al.

37. Microdrop Impact

38. Microdrop Impact and Spreading Velocity Scale Pressure Scale

39. Typical Microdrop Experiment (Dong et al 07) ? ?

40. Recovering Hidden Information

42. Periodically Patterned Surfaces No slip – No effect.No slip – No effect.

43. Interface Formation vs Molecular Dynamics Solid 2 less wettable Qualitative agreement

44. Surfaces of Variable Wettability 1 1.5

45. Flow Control on Patterned Surfaces

47. Capillary Rise

48. Flow Characteristics

49. ‘Hydrodynamic Resist’

52. Dynamic Wetting Models Washburn Model Basic Dynamic Wetting Models Interface Formation Model and Experiments Meniscus shape unchanged by dynamic wetting Meniscus shape dependent on speed of propagation. Meniscus shape influenced by geometry Equilibrium Dynamic Equilibrium Dynamic Equilibrium Dynamic Meniscus

53. Wetting Fronts Propagating Through Porous Media

54. Wetting Fronts in Porous Media Threshold ModeWetting Mode Wetting Front

55. Capillary Rise through Packed Beads Circles: Experimental data from Delker et al 1996 Line: Developed theory ) z Washburnian z (cm) t (s) Non- Washburnian

56. Flow over a Porous Substrate