Module 3: "Thin Film Hydrodynamics"
  Lecture 12: ""
 

Analysis of the terms in the dispersion relation

Consider the terms inside the braces in Eq. (3.13).

I st Term:

It represents the effect of gravity. If , this term would be positive and have a destabilizing effect (Rayleigh-Taylor instability). This situation could occur when, for example, there is a heavier liquid on top of a lighter one on a surface.

II Term:

It represents the effect of surface tension. For any positive interfacial tension this term would be negative and thus would have a stabilizing effect.

III Term:

If , it would have a destabilizing effect.

(3.14)

 

 

has the units of energy per unit volume. And is known as Hamaker constant and depends on the properties of the material.