docs: def Martin_Sims(m, x, D, rhol, rhog, hl):
      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}}{h_l} = 1 + 0.64\sqrt{\frac{V_{gs}}{V_{ls}}}
              
      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]
      hl : float
          Liquid-phase heat transfer coefficient as described below, [W/m^2/K]
  
      Returns
      -------
      h : float
          Heat transfer coefficient [W/m^2/K]
  
      Notes
      -----
      No suggestion for how to calculate the liquid-phase heat transfer
      coefficient is given in [1]_; [2]_ suggests to use the same procedure as
      in `Knott`, but this has not been implemented.
      
      Examples
      --------
      >>> Martin_Sims(m=1, x=.9, D=.3, rhol=1000, rhog=2.5, hl=141.2)
      5563.280000000001
  
      References
      ----------
      .. [1] Martin, B. W, and G. E Sims. "Forced Convection Heat Transfer to 
         Water with Air Injection in a Rectangular Duct." International Journal 
         of Heat and Mass Transfer 14, no. 8 (August 1, 1971): 1115-34. 
         doi:10.1016/0017-9310(71)90208-0.
      .. [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.
      '''
      Vgs = m*x/(rhog*pi/4*D**2)
      Vls = m*(1-x)/(rhol*pi/4*D**2)
      return hl*(1 + 0.64*(Vgs/Vls)**0.5)