def water(phase,
          pore_T='pore.temperature',
          pore_salinity='pore.salinity',
          **kwargs):
    r"""
    Calculates surface tension of pure water or seawater at atmospheric
    pressure using Eq. (28) given by Sharqawy et. al [1]_. Values at
    temperature higher than the normal boiling temperature are calculated at
    the saturation pressure.

    Parameters
    ----------
    pore_temperature : string
        The dictionary key containing the temperature values.  Temperature must
        be in Kelvin for this emperical equation to work

    pore_salinity : string
        The dictionary key containing the salinity values.  Salinity must be
        expressed in g of salt per kg of solution (ppt).

    Returns
    -------
    sigma_sw, the surface tension of seawater in [N/m]

    Notes
    -----
     T must be in K, and S in g of salt per kg of phase, or ppt (parts per
        thousand)
    VALIDITY: 273 < T < 313 K; 0 < S < 40 g/kg;
    ACCURACY: 0.2 %

    References
    ----------
    [1] Sharqawy M. H., Lienhard J. H., and Zubair, S. M., Desalination and
    Water Treatment, 2010.

    """
    T = phase['pore.temperature']
    try:
        S = phase['pore.salinity']
    except:
        S = 0
    sigma_w = 0.2358*((1-(T/647.096))**1.256)*(1-0.625*(1-(647.096/T)))
    a1 = 2.2637334337E-04
    a2 = 9.4579521377E-03
    a3 = 3.3104954843E-02
    TC = T-273.15
    sigma_sw = sigma_w*(1+(a1*TC+a2)*sp.log(1+a3*S))
    value = sigma_sw
    return value
dataset/ETHPy150Open PMEAL/OpenPNM/OpenPNM/Phases/models/surface_tension.py/water/swapped operands of `/`