washburn

openpnm.models.physics.capillary_pressure.washburn(target, surface_tension='pore.surface_tension', contact_angle='pore.contact_angle', diameter='throat.diameter')[source]

Computes the capillary entry pressure assuming the throat in a cylindrical tube.

Parameters

  • target (OpenPNM Base object) – Object with which this model is associated. This controls the length of the calculated array, and also provides access to other necessary properties.

  • surface_tension (str) – Name of the dictionary key on target pointing to the array containing values of surface tension. If a pore property is given, it is interpolated to a throat list.

  • contact_angle (str) – Name of the dictionary key on target pointing to the array containing values of contact angle. If a pore property is given, it is interpolated to a throat list.

  • diameter (str) – Name of the dictionary key on target pointing to the array containing values of throat diameter

Returns

values – A numpy ndarray containing the computed values of capillary entry pressure

Return type

ndarray

Notes

The Washburn equation is:

\[P_c = -\frac{2\sigma(cos(\theta))}{r}\]

This is the most basic approach to calculating entry pressure and is suitable for highly non-wetting invading phases in most materials.