# Aerofoil analysis, CFD and Experimental comparison

• Ma77h3w

## Homework Statement

Computational Fluid Dynamics anyone? :D I know someone out there is a genius?
I'm trying to understand some of the differences between Experimental results and a Fluent (CFD) analysis of a NACA 0012 aerofoil. There are 3 Cp/x graphs of my results (plotted with negative down just to confuse you - suction on bottom, pressure top) . I need to explain what causes the differences between CFD and the experiment. Fluent is set up with pretty standard settings, standard wall functions.. etc..

## The Attempt at a Solution

Here's what I've written so far (check attachments for graphs, hopefully they'll show up) :-

The 0º incidence results show a good similarity between the Fluent solver and the
experimental results. There is a small discrepancy with the experimental results showing a
lower Cp along the whole surface than the Fluent CFD. This may be due to... ?real-world surface roughness? ?Fluent wall functions? ... any ideas?

The 9º incidence results also show a good similarity between the CFD and the experiment.
However at the front tip of the wing the experimental results show a smaller Cp value than
the CFD on the suction surface. This may be due to ... no idea? anyone? my notes don't help!

The 12º incidence results show a large difference between CFD and the experiment. The Cp
on the suction surface is a lot nearer zero for the experiment, and flattens rather than
converging on zero. This is due to separation occurring on the suction surface of the
aerofoil. The standard wall functions used in Fluent don’t account for the separation
occurring in the 12º incidence case. Fluent’s non-equilibrium wall functions should be used
instead, as they provide a better estimation of the non-equilibrium effects in the separation.
... Not sure if there's anything I'm missing?

I will be amazingly greatful if anyone can help fill in the gaps.. :)
:)
Matt

Last edited:
i got a problem that there is offset in cp plots of Fluent and experiment regarding Naca65.
Please suggest what may be the cause