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-   -   Torque in a sliding interface mesh (http://www.cfd-online.com/Forums/openfoam-solving/57915-torque-sliding-interface-mesh.html)

antonio_ing February 11, 2009 08:53

Hi foamers i would like to
 
Hi foamers

i would like to measure the torque in a certain patch which belongs to a rotating region. I simulate a turbulent flow (with a standard kepsilon model) around some rotating airfoils with a sliding interface method. How can i measure the torque?

thanks is advance

maruthamuthu_venkatraman February 12, 2009 10:58

I have seen a thread that gave
 
I have seen a thread that gave a small routine you can add it on Control file. It write both Force and moments , you should specify the moment centre.

Today i am outof office, If u feel difficult in searching the thread then i will post it on monday.

maddalena February 12, 2009 11:09

I guess this is that thread!
 
I guess this is that thread!

antonio_ing February 23, 2009 04:19

Hi foamers i would like to
 
Hi foamers

i would like to measure the torque in a certain patch which belongs to a rotating region. I simulate a turbulent flow (with a standard kepsilon model) around some rotating airfoils with a sliding interface method. How can i measure the torque?

thanks is advance

maruthamuthu_venkatraman February 23, 2009 04:33

Hello Antonio, HAve a look
 
Hello Antonio,

HAve a look at it. Write them at the end of control file . Your forces and moments will be written in seperate folder. Remember to specify the axis of rotation of your rotor.

Hope this is what your are asking for ... Alsom set the patch name as you specified in the boundary files... for eg: Wall.

Good luck

functions // this one!
(
forces
{
type forces;
functionObjectLibs ("libforces.so"); //Lib to load
patches (building); // change to your patch name
rhoInf 1.225; //Reference density for fluid
CofR (0 0 0); //Origin for moment calculations
}
forceCoeffs
{
type forceCoeffs;
functionObjectLibs ("libforces.so");
patches (building); //change to your patch name
rhoInf 1.225;
CofR (0 0 0);
liftDir (0 1 0);
dragDir (1 0 0);
pitchAxis (0 0 0);
magUInf 11.2;
lRef 45;
Aref 45;
}
);

antonio_ing February 23, 2009 04:36

thx i was unsure if this co
 
thx

i was unsure if this code will work on rotating patches. I'll tell you soon... :-)

antonio_ing February 23, 2009 05:13

actually there is something st
 
actually there is something strange since the torque is lower than expected and, also, this is a 2d geometry so the only non zero torque component should be Mz but in this case all the three torque components are comparable.

maruthamuthu_venkatraman February 23, 2009 05:25

Just to make sure check the co
 
Just to make sure check the coordinates for the rotation axis. I used the above code for simple fixed cylinders and gave me reliable coeffcients. I hope it will work in the dev version also.

you can plot the coeffcients cd and cl over time and check for periodicity. Check your contours aswell. If all are correct then the above code need some more functional input for torque...

This is just a suggestion.

antonio_ing February 23, 2009 05:58

looking at the forces, the cen
 
looking at the forces, the centre of rotation is correct (0 0 0) and i can obtain the same result with the forceCoeffs. but the problem remains... :-(


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