def turbulent_Churchill_Zajic(Re, Pr, fd):
    """Calculates internal convection Nusselt number for turbulent flows
    in pipe according to [2]_ as developed in [1]_. Has yet to obtain
    popularity.

    .. math::
        Nu = \\left\\{\\left(\\frac{Pr_T}{Pr}\\right)\\frac{1}{Nu_{di}} +
        \\left[1-\\left(\\frac{Pr_T}{Pr}\\right)^{2/3}\\right]\\frac{1}{Nu_{D\\infty}}
        \\right\\}^{-1}

    .. math::
        Nu_{di} = \\frac{Re(f/8)}{1 + 145(8/f)^{-5/4}}

    .. math::
        Nu_{D\\infty} = 0.07343Re\\left(\\frac{Pr}{Pr_T}\\right)^{1/3}(f/8)^{0.5}

    .. math::
        Pr_T = 0.85 + \\frac{0.015}{Pr}

    Parameters
    ----------
    Re : float
        Reynolds number, [-]
    Pr : float
        Prandtl number, [-]
    fd : float
        Darcy friction factor [-]

    Returns
    -------
    Nu : float
        Nusselt number, [-]

    Notes
    -----
    No restrictions on range. This is equation is developed with more
    theoretical work than others.

    Examples
    --------
    >>> turbulent_Churchill_Zajic(Re=1E5, Pr=1.2, fd=0.0185)
    260.5564907817961

    References
    ----------
    .. [1] Churchill, Stuart W., and Stefan C. Zajic. “Prediction of Fully
       Developed Turbulent Convection with Minimal Explicit Empiricism.”
       AIChE Journal 48, no. 5 (May 1, 2002): 927–40. doi:10.1002/aic.690480503.
    .. [2] Plawsky, Joel L. Transport Phenomena Fundamentals, Third Edition.
       CRC Press, 2014.
    """
    Pr_T = 0.85 + 0.015 / Pr
    Nu_di = Re * (fd / 8.0) / (1.0 + 145 * (8.0 / fd) ** -1.25)
    Nu_dinf = 0.07343 * Re * (Pr / Pr_T) ** (1.0 / 3.0) * (fd / 8.0) ** 0.5
    return 1.0 / (Pr_T / Pr / Nu_di + (1.0 - (Pr_T / Pr) ** (2 / 3.0)) /
        Nu_dinf)
