Formula 1.8
Capillary number
Input(s)
$\mu_{w}$: Viscosity of Displacing Fluid $(\mathrm{cP})$
V: Characteristic Velocity (ft/D)
$\sigma_{o w}$: Surface or Interfacial Tension of Oil and Water Phases $(\mathrm{dyn} / \mathrm{cm})$
Output(s)
$\mathrm{N}_{\mathrm{c}}$: Capillary Number (dimensionless)
Formula(s)
$$ N c=\frac{\mu_{w} * V}{\sigma_{o w}} $$
Reference(s)
Wikipedia.org.