def eotvos(target, k, temperature='pore.temperature', critical_temperature=
    'pore.critical_temperature', molar_density='pore.molar_density'):
    """
    Missing description

    Parameters
    ----------
    target : OpenPNM Object
        The object for which these values are being calculated.  This
        controls the length of the calculated array, and also provides
        access to other necessary thermofluid properties.

    k : float
        Constant parameter specific to fluid

    temperature : string
        The dictionary key containing the temperature values (K)

    critical_temperature : string
        The dictionary key containing the critical temperature values (K)

    molar_density : string
        The dictionary key containing the molar density values (K)

    Returns
    -------
    value : NumPy ndarray
        Array containing surface tension values [N/m]

    TODO: Needs description, and improve definition of k

    """
    Tc = target[critical_temperature]
    T = target[temperature]
    Vm = 1 / target[molar_density]
    value = k * (Tc - T) / Vm ** (2 / 3)
    return value
