def Nu_cylinder_Churchill_Bernstein(Re, Pr):
    """Calculates Nusselt number for crossflow across a single tube
    at a specified `Re` and `Pr`, both evaluated at the film temperature. No
    other wall correction is necessary for this formulation. Method is
    shown without modification in [2]_ and many other texts.

    .. math::
        Nu_D = 0.3 + \\frac{0.62 Re_D^{0.5} Pr^{1/3}}{[1 + (0.4/Pr)^{2/3}
        ]^{0.25}}\\left[1 + \\left(\\frac{Re_D}{282000}\\right)^{5/8}\\right]^{0.8}

    Parameters
    ----------
    Re : float
        Reynolds number with respect to cylinder diameter, [-]
    Pr : float
        Prandtl number at film temperature, [-]

    Returns
    -------
    Nu : float
        Nusselt number with respect to cylinder diameter, [-]

    Notes
    -----
    May underestimate heat transfer in some cases, as it the formula is
    described in [1]_ as "appears to provide a lower bound for RePr > 0.4".
    An alternate exponent for a smaller range is also presented in [1]_.

    This method applies to both the laminar and turbulent regimes.

    Examples
    --------
    Example 7.3 in [2]_, matches.

    >>> Nu_cylinder_Churchill_Bernstein(6071, 0.7)
    40.63708594124974

    References
    ----------
    .. [1] Churchill, S. W., and M. Bernstein. "A Correlating Equation for
       Forced Convection From Gases and Liquids to a Circular Cylinder in
       Crossflow." Journal of Heat Transfer 99, no. 2 (May 1, 1977):
       300-306. doi:10.1115/1.3450685.
    .. [2] Bergman, Theodore L., Adrienne S. Lavine, Frank P. Incropera, and
       David P. DeWitt. Introduction to Heat Transfer. 6E. Hoboken, NJ:
       Wiley, 2011.
    """
    return 0.3 + 0.62 * Re ** 0.5 * Pr ** (1 / 3.0) / (1 + (0.4 / Pr) ** (2 /
        3.0)) ** 0.25 * (1 + (Re / 282000.0) ** 0.625) ** 0.8
