r'''Calculates critical heat flux for nucleic boiling of a flat plate
    or other shape as presented in various sources.
    K = pi/24 is believed to be the original [1]_ value for K, but 0.149 is
    now more widely used, a value claimed to be from [2]_ according to [5]_.
    Cao [4]_ lists a value of 0.18 for K. The Wolverine Tube data book also
    lists a value of 0.18, and so it is the default.

    .. math::
        q_c = 0.149H_{vap} \rho_g^{0.5}\left[\sigma g (\rho_L-\rho_g)\right]^{0.25}

    Parameters
    ----------
    sigma : float
        Surface tension of liquid [N/m]
    Hvap : float
        Heat of vaporization of the fluid at P, [J/kg]
    rhol : float
        Density of the liquid [kg/m^3]
    rhog : float
        Density of the produced gas [kg/m^3]
    K : float
        Constant []

    Returns
    -------
    q: float
        Critical heat flux [W/m^2]

    Notes
    -----
    No further work is required on this correlation. Multiple sources confirm
    its form.

    Examples
    --------
    Example from [3]_

    >>> Zuber(sigma=8.2E-3, Hvap=272E3, rhol=567, rhog=18.09, K=0.149)
    444307.22304342285
    >>> Zuber(sigma=8.2E-3, Hvap=272E3, rhol=567, rhog=18.09, K=0.18)
    536746.9808578263

    References
    ----------
    .. [1] Zuber N. "On the stability of boiling heat transfer". Trans ASME 1958
        80:711-20.
    .. [2] Lienhard, J.H., and Dhir, V.K., 1973, Extended Hydrodynamic Theory
       of the Peak and Minimum Heat Fluxes, NASA CR-2270.
    .. [3] Serth, R. W., Process Heat Transfer: Principles,
       Applications and Rules of Thumb. 2E. Amsterdam: Academic Press, 2014.
    .. [4] Cao, Eduardo. Heat Transfer in Process Engineering.
       McGraw Hill Professional, 2009.
    .. [5] Kreith, Frank, Raj Manglik, and Mark Bohn. Principles of Heat
       Transfer, 7E.Mason, OH: Cengage Learning, 2010.

def Zuber(sigma, Hvap, rhol, rhog, K=0.18):
    r'''Calculates critical heat flux for nucleic boiling of a flat plate
    or other shape as presented in various sources.
    K = pi/24 is believed to be the original [1]_ value for K, but 0.149 is
    now more widely used, a value claimed to be from [2]_ according to [5]_.
    Cao [4]_ lists a value of 0.18 for K. The Wolverine Tube data book also
    lists a value of 0.18, and so it is the default.

    .. math::
        q_c = 0.149H_{vap} \rho_g^{0.5}\left[\sigma g (\rho_L-\rho_g)\right]^{0.25}

    Parameters
    ----------
    sigma : float
        Surface tension of liquid [N/m]
    Hvap : float
        Heat of vaporization of the fluid at P, [J/kg]
    rhol : float
        Density of the liquid [kg/m^3]
    rhog : float
        Density of the produced gas [kg/m^3]
    K : float
        Constant []

    Returns
    -------
    q: float
        Critical heat flux [W/m^2]

    Notes
    -----
    No further work is required on this correlation. Multiple sources confirm
    its form.

    Examples
    --------
    Example from [3]_

    >>> Zuber(sigma=8.2E-3, Hvap=272E3, rhol=567, rhog=18.09, K=0.149)
    444307.22304342285
    >>> Zuber(sigma=8.2E-3, Hvap=272E3, rhol=567, rhog=18.09, K=0.18)
    536746.9808578263

    References
    ----------
    .. [1] Zuber N. "On the stability of boiling heat transfer". Trans ASME 1958
        80:711-20.
    .. [2] Lienhard, J.H., and Dhir, V.K., 1973, Extended Hydrodynamic Theory
       of the Peak and Minimum Heat Fluxes, NASA CR-2270.
    .. [3] Serth, R. W., Process Heat Transfer: Principles,
       Applications and Rules of Thumb. 2E. Amsterdam: Academic Press, 2014.
    .. [4] Cao, Eduardo. Heat Transfer in Process Engineering.
       McGraw Hill Professional, 2009.
    .. [5] Kreith, Frank, Raj Manglik, and Mark Bohn. Principles of Heat
       Transfer, 7E.Mason, OH: Cengage Learning, 2010.
    '''
    return K*Hvap*rhog**0.5*(g*sigma*(rhol-rhog))**0.25