docs: def Davis_David(m, x, D, rhol, rhog, Cpl, kl, mul):
      r'''Calculates the two-phase non-boiling heat transfer coefficient of a 
      liquid and gas flowing inside a tube of any inclination, as in [1]_ and 
      reviewed in [2]_.
  
      .. math::
          \frac{h_{TP} D}{k_l} = 0.060\left(\frac{\rho_L}{\rho_G}\right)^{0.28}
          \left(\frac{DG_{TP} x}{\mu_L}\right)^{0.87}
          \left(\frac{C_{p,L} \mu_L}{k_L}\right)^{0.4}
          
      Parameters
      ----------
      m : float
          Mass flow rate [kg/s]
      x : float
          Quality at the specific tube interval [-]
      D : float
          Diameter of the tube [m]
      rhol : float
          Density of the liquid [kg/m^3]
      rhog : float
          Density of the gas [kg/m^3]
      Cpl : float
          Constant-pressure heat capacity of liquid [J/kg/K]
      kl : float
          Thermal conductivity of liquid [W/m/K]
      mul : float
          Viscosity of liquid [Pa*s]
  
      Returns
      -------
      h : float
          Heat transfer coefficient [W/m^2/K]
  
      Notes
      -----
      Developed for both vertical and horizontal flow, and flow patters of 
      annular or mist annular flow. Steam-water and air-water were the only 
      considered fluid combinations. Quality ranged from 0.1 to 1 in their data.
      [1]_ claimed an AAE of 17%.
  
      Examples
      --------
      >>> Davis_David(m=1, x=.9, D=.3, rhol=1000, rhog=2.5, Cpl=2300, kl=.6, 
      ... mul=1E-3)
      1437.3282869955121
  
      References
      ----------
      .. [1] Davis, E. J., and M. M. David. "Two-Phase Gas-Liquid Convection Heat
         Transfer. A Correlation." Industrial & Engineering Chemistry 
         Fundamentals 3, no. 2 (May 1, 1964): 111-18. doi:10.1021/i160010a005.
      .. [2] Dongwoo Kim, Venkata K. Ryali, Afshin J. Ghajar, Ronald L. 
         Dougherty. "Comparison of 20 Two-Phase Heat Transfer Correlations with 
         Seven Sets of Experimental Data, Including Flow Pattern and Tube 
         Inclination Effects." Heat Transfer Engineering 20, no. 1 (February 1, 
         1999): 15-40. doi:10.1080/014576399271691.
      '''
      G = m/(pi/4*D**2)
      Prl = Prandtl(Cp=Cpl, mu=mul, k=kl)
      Nu_TP = 0.060*(rhol/rhog)**0.28*(D*G*x/mul)**0.87*Prl**0.4
      return Nu_TP*kl/D