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-   -   Flow Over Airfoil With Simple Flap Results (https://www.cfd-online.com/Forums/fluent/35820-flow-over-airfoil-simple-flap-results.html)

 fez February 22, 2005 08:18

Flow Over Airfoil With Simple Flap Results

I have just done my iterations FLUENT has at last converged!

I now dont know what to do...

The point of my project is to find and discuss the pressure distribution along the surface of the air foil..the velocity profile, boundary layers etc....

I know how to make line/rakes along the airfoil but dont know how to plot this data in MS Excel...i know how import the data into Excel but dont know how rearrange and plot....

Does anyone know how to do and what to do or is there a guide of some sort that shows how to display my results in a presentable form?

Any help would be great!

 Jason February 22, 2005 13:22

Re: Flow Over Airfoil With Simple Flap Results

I'm assuming you're importing the XY Plot data from Fluent into Excel... There's a "sort data" option in the XY plot window... it's worth a try, but I've never had it give me the results I'm looking for... the best way I've found is to import the data into Excel and sort it there... highlight both columns of data (just the data, not the headers), then go to Data->Sort. Then you can pick which column to sort by and if you want the data in Ascending or Descending order.

Hope this helps, and goodluck, Jason

 fez February 23, 2005 09:08

Re: Flow Over Airfoil With Simple Flap Results

Hi Jason!

I have exported the line/rake data of the velocity magnitudes of the air flow over and under the airfoil and the pressure distribution. I was wondering if you know what i do next in MS Excel to find the Cp and Cl and Cd values...because the Cl and Cd values in Fluent look incorrect.

What formulas do i use?????

Thanks for ur help!

 Jason February 23, 2005 11:56

Re: Flow Over Airfoil With Simple Flap Results

Cl = Lift/(Qfreestream*Aref) Cd = Drag/(Qfreestream*Aref)

Where Lift and Drag are integrations of the pressure and viscous forces along the surface. That one you'll have to work out on your own if you're going to do it, but I don't think it's worth the effort unless you've got a faculty advisor breathing down your neck to do it or something. Fluent's integration algorithms are tried-and-true.

Cp = (P-Pref)/Qfreestream or (Pgage)/Qfreestream where Qfreestream = 1/2*rho*Vfreestream^2

Odds are the Cl and Cd don't look correct because you didn't set your reference values... could be the same thing if you're having problems with Cp... They are under Report->Reference Values. Also, check to make sure your grid is the right scale. Fluent assumes meters when it imports the grid... if you didn't use meters when you modeled it, and you didn't scale it when you imported it, then that's gonna be a problem too.

Hope this helps, and goodluck, Jason

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