If inserts are used, the friction factor is calculated according to Manglik and Bergles (Journal of Thermal Science and Egineering Applications 2013 Vol.5). For laminar flow, the constant power equation is used with a 0.8 factor, in order to allow for lower exchange in constant wall temperature situations. Otherwise the friction factor is calculated as per Churchill's equation.
A correction factor for wall viscosity can be used.
The heat transfer coefficient is calculated according to Manglik and Bergles if tape inserts are used, or according to Gnielinsky and others if not. Interpolation between laminar and turbulent flow is used. A fouling factor and a wall viscosity correction factor can also be used.
.FreeFluids.Pipes.PipeForcedConvection