Smooth rectabgular duct - Simulation vs. Literature correlations
 

Hallo,

I have done simulations of a turbulent air flow in a smooth rectangular duct. I compared my numerical results of pressure drop (friction factor) with literature correlations.

Here follows a brief summary of my simulation (because of symmetry I have only simulated one-fourth of the duct):

Fluid: air with costant properties
Turb model: k-w standard
y+: everywhere below 2.5 and above 0.8
Inlet B.C.: mass flow inlet
Outlet B.C.: outflow
Reynolds number: 7666

I compared my results for the pressure drop (or friction factor) with some literature correlations, e.g. f=(1.82*log_10 Re -1.64)^-2 (Gnielinski) and I have foud a mean discrepancy of 12%.

I have also performed a sensitivity analysis on the grid but the results do not change.

Can anyone inform me if such a discrepancy is acceptable or if it is typically possible to obtain a better agreement between numerical simulation and literature correlation for the friction factor (or pressure drop)?

Thank you in advance,
marluc

Hello, I'm sorry to bother you. Although this has been a post for many years, I have also encountered similar situations. Can you tell me how you resolved this issue in the end?

You have to make sure you are comparing apples to apples.
Make sure your inlet or outlet effects are not influencing your results comparisons, and total pressure effects from changing cross sections or compressible flows are also considered correctly in the comparison.