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-   -   [mesh manipulation] Coordinate system definition in porous zones (https://www.cfd-online.com/Forums/openfoam-meshing/154440-coordinate-system-definition-porous-zones.html)

mp001 June 14, 2015 18:30

Coordinate system definition in porous zones
 
Hi,

I'm new with openFOAM and cfd :). As assignment for a university course, I should simulate a DOC-DPF system (teacher gave me a tutorial). I have set the porous zone in that way:

porosity1
{
type DarcyForchheimer;
active yes;
cellZone catZoneCells;

DarcyForchheimerCoeffs
{
d d [0 -2 0 0 0 0 0] (2e8 1e8 1e8);
f f [0 -1 0 0 0 0 0] (0 0 0);

coordinateSystem
{
e1 (0.866 0.5 0); // asse cilindro
e2 (0 0 1); // ortogonale a e1
}
}
}

I did not completely understand the meaning of e1 and e2. I think these unitary vectors are the local coordinate system of the zone, but how can I set the origin of the system?
What is the kind of relation they have with the global system?

Thanks to all!

Best regards,
Matteo.

mizzou October 9, 2016 18:18

Quote:

Originally Posted by mp001 (Post 550313)
Hi,

I'm new with openFOAM and cfd :). As assignment for a university course, I should simulate a DOC-DPF system (teacher gave me a tutorial). I have set the porous zone in that way:

porosity1
{
type DarcyForchheimer;
active yes;
cellZone catZoneCells;

DarcyForchheimerCoeffs
{
d d [0 -2 0 0 0 0 0] (2e8 1e8 1e8);
f f [0 -1 0 0 0 0 0] (0 0 0);

coordinateSystem
{
e1 (0.866 0.5 0); // asse cilindro
e2 (0 0 1); // ortogonale a e1
}
}
}

I did not completely understand the meaning of e1 and e2. I think these unitary vectors are the local coordinate system of the zone, but how can I set the origin of the system?
What is the kind of relation they have with the global system?

Thanks to all!

Best regards,
Matteo.

I also have the same question. Anybody have any idea to clarify the problem?

Thank you,

Shadab December 29, 2017 02:12

Hello everyone,

Guys Please help me with the how to set the origin, e1, e2, and e3.

tomf January 1, 2018 09:59

Quote:

porosity1
{
type DarcyForchheimer;
active yes;
cellZone catZoneCells;

DarcyForchheimerCoeffs
{
d d [0 -2 0 0 0 0 0] (2e8 1e8 1e8);
f f [0 -1 0 0 0 0 0] (0 0 0);

coordinateSystem
{
e1 (0.866 0.5 0); // asse cilindro
e2 (0 0 1); // ortogonale a e1
}
}
}

Hi,

e1 is the direction in which the first entry of the "d" and "f" vectors are acting. So in direction e1 d is 2e8, in direction e2 it is 1e8 and in direction e3 (which is perpendicular to the plane defined by e1 and e2) we also have 1e8.

The Forchheimer coefficients are 0 in all directions. The current setup means that there is more resistance in the e1 direction than in the other directions.

Hope this helps.

Regards,
Tom

Shadab January 3, 2018 02:43

Hello Tom,

Thank you very much for your quick reply and suggestion, the Chalmers University material by Haukur Elvar Hafsteinsson will give a brief details about how to setup and used in OpenFOAM.

The link for the material given below

http://www.tfd.chalmers.se/~hani/kur...ukurReport.pdf


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