washburn#

washburn(phase, surface_tension='throat.surface_tension', contact_angle='throat.contact_angle', diameter='throat.diameter')[source]#

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

Parameters:

  • phase (OpenPNM Phase object) – The phase object to which this model is associated (i.e. attached). This controls the length of the calculated array(s), and also provides access to other necessary properties.

  • surface_tension (str) – Name of the dictionary key on the target object 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 the target object 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 the target object 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.

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