5.5.1 Definitions
- Component: A fluid that is immiscible with other fluids. Examples of a component include air, water and oil.
-
Mixture: The fluid created by the combination of all the components in a volume or at a boundary.
-
Phase Mass: The total mass of a component within a selected volume.
- Phase Volume: The total volume of component within a selected volume.
-
Mass Fraction: The mass of a component divided by the total mass within a selected volume.
-
Volume Fraction: The volume of a component divided by the total volume.
-
Contact Angle: A contact angle of
corresponds to full wetting (e.g. hydrophilic) and 
corresponds to no wetting (e.g. hydrophobic). A contact angle between 0 and 180 corresponds to partial wetting., see Figure 5.97. -
Weber Number: The strength of momentum relative to surface tension. A small Weber number (
) implies that the surface tension forces are relatively strong compared to the momentum.
5.249
where
Density (kg/m3) 
Free stream velocity (m/s) 
Representative length scale (m) 
Surface tension (N/m) -
Bond Number or Eötvös Number: The strength of gravity relative to surface tension. A small Bond number (
) or Eötvös number (
) implies that the surface tension forces are relatively strong compared to gravity.
5.250
where
Density (kg/m3) 
Gravity (m/s2) 
Representative length scale (m) 
Surface tension (N/m)
