Fluid Properties
Fluids are assumed to be Newtonian, single-phase, and non-reacting. Custom inputs override standard temperature-dependent properties. For compressible flow, Air is treated as an ideal gas with constant specific heats (Calorically Perfect).
Turbulence Initialization
The empirical correlation I = 0.16 Re^(-1/8) is intended for fully developed pipe flow. For external aerodynamics, a lower freestream turbulence (0.1% - 1%) is usually more appropriate unless grid turbulence is present.
Solver Conventions
OpenFOAM: Expects explicit k, ε, ω values in standard SI units. Fluent/STAR: UI usually abstracts this by accepting Intensity and Length Scale directly, though providing explicit turbulent viscosity ratios can aid initial convergence.
Thermal Limitations
The Dittus-Boelter equation is a simplified correlation. It loses accuracy for liquid metals (Pr << 1) or highly viscous oils (Pr >> 160), and does not account for massive property variations across the boundary layer.