[ericnutsch]

Hello Aldo,

Originally Posted by aldo.iannetti

I'm studing a vertical axis wind turbine 2D, I have an internal-rotational zone and an external-static zone and the interfaces have been modelled as GGI.

Me too! Sounds like we are at about the same stage of testing as well.


So does your ggi model work without the turbulence model?
I have gotten a k-e turbulence model to work with the ggi. Once I know more specifically where your hung up I can help.

Im in the process of testing the ggi interface with the turbulence model and so far so good.


Ive signed an NDA on the VAWT design, but I would certainly like to correspond on our solving methods; ericnutsch@gmail.com

[NickG]

Hi Aldo

I don't bother to specify a value for any of the /0/ files - just: type ggi;

The important part is specifying correct values for k and epsilon (or omega)

My understanding is that you set the internalField as:

for k:

1.5(magUI)^2 where magU is the magnitude of the velocity
I is the turbulence intensity

for epsilon:

(Cmu^0.75)(k^1.5)/L where Cmu =0.09 (see /constant/RASProperties)
k is worked out through previous
L is the characteristic length that you'd use for the Reynolds number

for omega if you need it later:

(Cmu^-0.25)(k^0.5)/L

Good luck! Let us know if it works

Nick

[A.Devesa]

Hi all,

i'm simulating the propeller of an HAWT using GGI / turbDyMFoam, and i'm quite surprised that the wake of my blades is almost unexisting (e.g. no wing-tip structures) for a lambda of around 7 (lambda = Vwingtip / Vinf)...

Could you please briefly share your experience on GGI for simulating WT?
- Which turbulence model are you using?
- Which BC on the rotating elements?
- Which lambda?
- Which level of initial / inlet turbulence?
- Are you satisfied of your results?

Thank you for your answers!!
Antoine

[ericnutsch]

You are a bit ahead of me. I am currently modelling in 2D with a k-epsilon model. I have yet to confirm its performance with wind tunnel testing, but I will keep everyone posted.

You may want to test that the turbulence values are passing the interface at all, or if there is a time delay. This will give you an idea of where the issue lies...

For 3D i believe you will want to use a LES turbulence model, but i have not tested any with the ggi.

[A.Devesa]

Ok, thanks for keeping posting, it's really interesting.

On my side, i want first to success using RAS approach, before i go to LES. Moreover it's actually not yet possible to use GGI in comibnation with LES, is it?

Any other experience to share, concerning 3D RAS simulations of WT with GGI and turbDyMFoam?

[shyam]

Hi Foamers,
Does turboDyMFoam work in OF-1.6?

[NickG]

Hi Shyam - I'm afraid not.

[jiejie]

Originally Posted by Stylianos

I think i found what my mistake was. It seems the name of the rotating domain in cellZones is hardcoted in the code as movingCells.

So you just have to go in constant/polymesh/cellZones and rename the whatever name of your rotating domain into movingCells.

Stelios

Dear Stelios

After I renamed it into movingCells and ran the simulation, I found that the stator is rotating as well. Then I compared the 3d case with 2d case for a very simple rotating block case, i found after I convert the fluent mesh to the OpenFOAM conpatable, the cellZones (should only include the cells from rotator only) include all the cells from both stator and rotor, which causes such problem.

Have you experienced this before? Will it be due to the meshing problem? I used the icemcfd.

I have upload the case at http://www.megaupload.com/?d=2IIU3UVC

Really appreciate if you can have a look at it.

[jiejie]

I am not sure whether it is the meshing problem or not. Now I can make the stator to be stationary by re-initialise the /constant/polyMesh/cellZones with the followings:

##########

FoamFile
{
version 2.0;
format ascii;
class regIOobject;
location "constant/polyMesh";
object cellZones;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

0
(
)
//************************************************** ********************//

##########

Then, the cellZones will be re-written with the celld from rotor part.

Cheers