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3D simulation with blended wingbody. Lift a 1/3 of what it shuld be. Any wrong?

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Old   July 26, 2011, 08:21
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s.rasoul_varedi
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why there is difference between patchIntegrate results and the results of forces due to added force function in controlDict??? i was confused???
why this happened? can every one explained briefly why the resuls is different???
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Old   July 26, 2011, 17:25
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Forces calculates forces in Newtons

patchIntegrate integrates the chosen field over a chosen patch. if your case uses P/rho instead of just plain P, you will have a 1/rho difference between results.
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Old   September 12, 2011, 17:29
Default I found the wrong om my simulation ...
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Rickard Hidefjäll
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Itś so simple that I was traped by my own expectation.

The explanation is that the cl factor is less then you have a short wingspan.
For a example: I did a setup with a 10 meter wingspan and a length on 1 meter.
and a naca 0009. (seen from above). And 6 degree of angel of attack, 30 m/s. And got cl=0.398105.
When I scaled down to a 10:th i.e. 1 meter span and a length of 1 meter I got 0.1271.
After that I scaled down to a span 1 meter an a length of 0.1 meter and got a cl= 0.38623.
That is exactly correct according to a Nasa full scale wind tunnel measuring.

This was some thing i already known but forgot, because I experted a high drag an a slighter higher lift according to the vortex on the wing,
which Ì sort of did according to the square meter wing, when I got cl=0.21 for my wing .

Prismatic layer did`n change a bit.. I tried a lot of different values. And blockmesh is much better than netgen. At least in my cases.
With netgen I could not simulate a wing with less angel of attack than 5 degree. There was no limit according to blockMesh.

Regards / Rickard
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