Related Experiment Video
Updated: Oct 29, 2025

Microtensiometer for Confocal Microscopy Visualization of Dynamic Interfaces
Published on: September 9, 2022
Capillary pressure, osmotic pressure and bubble contact areas in foams
Reinhard Höhler1, Jordan Seknagi2, Andrew Kraynik3
1Sorbonne Universités, UPMC Univ Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris, 4 place Jussieu, 75005 Paris, France and Université Gustave Eiffel, 5 Bd Descartes, Champs-sur-Marne, F-77454 Marne-la-Vallée cedex 2, France.
Abstract:
The capillary pressure of foams and emulsions is the difference between the average pressure in the dispersed phase and the pressure in the continuous phase. The pressure difference between individual bubbles or drops and the continuous phase is due to interfacial tension, and governs the thickness of films that separate neighbouring particles. Princen and Derjaguin presented an analytic relation, validated for ordered monodisperse foams with face-centered cubic (fcc) structure, that links the capillary pressure to osmotic pressure; they conjectured that it also held for disordered polydisperse foams that are encountered more frequently in nature and applications. Their conjecture is widely accepted. We derive their relation from first principles, and use known empirical expressions for the osmotic pressure to obtain analytic predictions for the capillary pressure and the average bubble contact area in a foam over the full range of liquid fractions. These results are validated using Surface Evolver simulations and previous experimental data. They also apply to emulsions.
More Related Videos
10:06Microfluidic Fabrication Techniques for High-Pressure Testing of Microscale Supercritical CO2 Foam Transport in Fractured Unconventional Reservoirs
Published on: July 2, 2020
08:38Microfluidic Devices for Characterizing Pore-scale Event Processes in Porous Media for Oil Recovery Applications
Published on: January 16, 2018
Related Concept Videos
Excess Pressure Inside a Drop and a Bubble
Capillarity in Fluid
Surface tension is crucial to capillarity. It results from cohesive forces between liquid molecules at the liquid-air boundary, forming a skin that resists external forces. When the capillary tube...
Surface Tension of Fluid
Surface tension varies...
Surface Tension, Capillary Action, and Viscosity
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
Capillary Exchange
Osmosis and Osmotic Pressure of Solutions