docs: def turbulent_Churchill_Zajic(Re, Pr, fd):
      r'''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}
  
          Nu_{di} = \frac{Re(f/8)}{1 + 145(8/f)^{-5/4}}
  
          Nu_{D\infty} = 0.07343Re\left(\frac{Pr}{Pr_T}\right)^{1/3}(f/8)^{0.5}
  
          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.)/(1. + 145*(8./fd)**(-1.25))
      Nu_dinf = 0.07343*Re*(Pr/Pr_T)**(1./3.0)*(fd/8.)**0.5
      return 1./(Pr_T/Pr/Nu_di + (1. - (Pr_T/Pr)**(2/3.))/Nu_dinf)