text: r"""
  """
  import numpy as _np
  
  
  def cylinder(target, throat_diameter='throat.diameter',
               throat_length='throat.length'):
      r"""
      Calculate surface area for a cylindrical throat
  
      Parameters
      ----------
      target : OpenPNM Object
          The object which this model is associated with. This controls the
          length of the calculated array, and also provides access to other
          necessary properties.
  
      throat_diameter : string
          Dictionary key to the throat diameter array.  Default is
          'throat.diameter'.
  
      throat_length : string
          Dictionary key to the throat length array.  Default is 'throat.length'.
  
      Returns
      -------
      value : NumPy ndarray
          Array containing throat surface area values.
  
      """
      return _np.pi * target[throat_diameter] * target[throat_length]
  
  
  def cuboid(target, throat_diameter='throat.diameter',
             throat_length='throat.length'):
      r"""
      Calculate surface area for a cuboid throat
  
      Parameters
      ----------
      target : OpenPNM Object
          The object which this model is associated with. This controls the
          length of the calculated array, and also provides access to other
          necessary properties.
  
      throat_diameter : string
          Dictionary key to the throat diameter array.  Default is
          'throat.diameter'.
  
      throat_length : string
          Dictionary key to the throat length array.  Default is 'throat.length'.
  
      Returns
      -------
      value : NumPy ndarray
          Array containing throat surface area values.
  
      """
      return 4 * target[throat_diameter] * target[throat_length]
  
  
  def extrusion(target, throat_perimeter='throat.perimeter',
                throat_length='throat.length'):
      r"""
      Calculate surface area for an arbitrary shaped throat give the perimeter
      and length.
  
      Parameters
      ----------
      target : OpenPNM Object
          The object which this model is associated with. This controls the
          length of the calculated array, and also provides access to other
          necessary properties.
  
      throat_perimeter : string
          Dictionary key to the throat perimeter array.  Default is
          'throat.perimeter'.
  
      throat_length : string
          Dictionary key to the throat length array.  Default is 'throat.length'.
  
      Returns
      -------
      value : NumPy ndarray
          Array containing throat surface area values.
  
      """
      return target[throat_perimeter] * target[throat_length]
  
  
  def rectangle(target, throat_length='throat.length'):
      r"""
      Calculate surface area for a rectangular throat
  
      Only suitable for true 2D simulations
  
      Parameters
      ----------
      target : OpenPNM Object
          The object which this model is associated with. This controls the
          length of the calculated array, and also provides access to other
          necessary properties.
  
      throat_length : string
          Dictionary key to the throat length array.  Default is 'throat.length'.
  
      """
      return 2 * target[throat_length]
  