Capillarity and Wetting

CBE773 Recent Topics in CBE

(Capillarity and Wetting Phenomena)

Fall Semester 2014

Instructor: Shin-Hyun Kim

Class will meet at 1:00 p.m. in 1119 on Mondays and Wednesdays.

Lecture notes and notices


· Pierre-Gilles de Gennes, Francoise Brochard-Wyart, and David Quere: Capillarity and Wetting Phenomena: drops, bubbles, pearls, waves, Springer, New York, NY (2004).


· Henrik Bruus: Theoretical Microfluidics, Oxford University Press, New York (2008).

· Richard A. Jones: Soft Condensed Matter, Oxford University Press, New York (2002).

General description for course: We frequently observe various interesting interfacial phenomena in everyday life. For example, we have watched a jet formation and its breakup into small drops at the leaky faucet. However, most people haven’t thought about the physical origin of the breakup (it is well-known as Plateau-Rayleigh instability). In this course, we will study basic physics of fluid interface and get insight to understand these phenomena related with capillarity and wetting phenomena. In addition, we will study how to control and design our experiments, based on the understanding. The course will begin with the basic science of interfacial tension and Laplace pressure. To understand dynamics of deformable interfaces, we will cover a few famous problems of hydrodynamics of interfaces, including instability problems and coating problems. In addition, we will discuss recent progress in this field. To help understand these phenomena, we will use lots of images, movies and simulation tools (Surface Evolver). The scope of this course is outlined below.

Course Outline

1. General Introduction (Chapter 1)

A. Surface tension

B. Surface energy and capillary force

C. Curvature and Laplace pressure

D. Wetting and spreading parameter

2. Capillarity and Gravity (Chapter 2)

A. Capillary length

B. Menisci

C. Capillary rise

D. Techniques for measuring surface tensions

1) Pendant drop method

2) Force measurements

3) Pressure measurements

3. Hysteresis and Wetting (Chapter 3 and 4)

A. Hysteresis: advancing and receding angles

B. Disjoining pressure

C. Total and partial wetting

D. Long-range forces

1) van der Waals forces

2) Electrostatic forces

4. Hydrodynamics of Interfaces (Chapter 5)

A. Lubrication approximation

B. Dynamics of thin film

1) Vertical film: thinning

2) Horizontal film: ripples

3) Rayleigh-Taylor instability

4) Plateau-Rayleigh instability

C. Forced Wetting

1) Capillary number and Weber number

2) Film formation on plate, fiber, and tube

D. Dynamics of capillary rise

5. Dewetting (Chapter 7)

A. Film on a solid substrate

B. Film on a liquid substrate

C. Viscous dewetting

D. Inertial dewetting

6. Surfactant (Chapter 8)

A. Hydrophilic/Lipophilic balance (HLB)

B. Assembly of surfactants

1) Aggregation in volume

2) Stabilization of free interfaces

C. Applications of surfactants

D. Soap films and bubbles

7. Special Interfaces (Chapter 9)

A. Textured surface: basic models

B. Superhydrophilic surfaces and superhydrophobic surfaces

8. Transport Phenomena (Chapter 10)

A. Chemical gradient

B. Thermal gradient

C. Reactive wetting