lift and drag

How it's possible to calculated the lift and drag of a aérodynamic profil (GAW-1) with the saturne code ?

Hello.

I am answering a bit late, nonetheless here is an example of stress calculation on a set of boundary faces.
[code:1]
CALL GETFBR('2 or 3',NLELT,LSTELT)
C ===========
DO ILELT = 1, NLELT
IFAC = LSTELT(ILELT)
DO II = 1, NDIM
XFOR(II) = XFOR(II) + RA(IFORBR + (IFAC-1)*NDIM + II-1)
ENDDO
ENDDO
IF (IRANGP.GE.0) THEN
CALL PARRSM(NDIM,XFOR)
ENDIF
[/code:1]
This will give you the total global stress (pressure, viscous terms, turbulence, ...) in the XFOR array by summing the contribution of each face from the local stress array via the IFORBR pointer and these contributions are summed over the processors if necessary. You then need to project this stress on you velocity in order to get the lift component (and the drag one).

I hope this helps.

David<br /><br />Post edited by: David Monfort, at: 2008/11/11 19:25

Sory but i am not enough clever to understand the way, how to insert the code &quot;CALL GEFTER&quot; in the &quot;code saturne wizard&quot;. I am not computer scientist
first i read code saturne documentation (pg 104) and some info about fortran language.
how i try to do it:
1.When i build the GAW-1 airfoil i divide it in 2 colors (color 2 for intrados and 3 for extrados)
2. I specified it in the definition of the boundary by ( labell : gaw-1 - zone : 4 - nature : Wall - localisation : 2 or 3)
3. inlet velocity components u=66 m/s and v= 5 m/s in the aim to have a angle off attack of 4° ?
4. When i reach lance : prepare batch calculation i select &quot;user files&quot; and there i try to put in the &quot;new data file&quot; the code you give me.
-First i copy the code &quot;CALL GEFTER...&quot; in a Vi editor or in the Kwrite then i compile via ARK and then i try to put in the&quot; user files&quot; but i receive a WARNING verify existence and location...
bref I am lost!

Questions :
My be, this is not the god way to do ?
What are the mistakessss ?
thank for the help

Hello,

Sorry for the late answer again, but I've been quite busy lately with few spare time for Code_Saturne support...

The example I gave you was a computation of the global stress on the airfoil. It should be set in the usproj.F file, that you copy from the FORT/USERS/base directory to the FORT directory. Then, the code will compile it and compute the global stress. I think there should be an example in the latest version of Code_Saturne (1.3.3 or 1.4.0, available on the website)

Nonetheless, I would advise you to compute the lift and drag directly in the post-processing stage. It might be easier.
Indeed, if you check the box in the graphical user interface corresponding to the post-processing of the boundary faces, Code_Saturne will output the global stress., visually.

Is it a bit clearer for you ?
David

for me your answer is never late
When in the code saturne: I select a speed “u” e.g. 30 m/s and for a certain number of iteration e.g. 60
I have a good resolution of pressure and velocity but for other input e.g. 66 m/s and iteration 100
I have on a specific point of the leading edge some informations and the same value for the rest of the airfoil ? WHY
If the picture off the pressure is not good. that mean that the result, in the listing, are wrong also ?
When I monitor some points off coordinates x,y,z. In the “HIST” I have some pressure results, can I take it account to calculate the lift?
Thanks for help