# [mesh manipulation] Coordinate system definition in porous zones

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 June 14, 2015, 18:30 Coordinate system definition in porous zones #1 New Member   Join Date: Jun 2015 Posts: 1 Rep Power: 0 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 likes this.

October 9, 2016, 18:18
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Quote:
 Originally Posted by mp001 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,

 December 29, 2017, 02:12 #3 New Member   Shadab Mohammed Join Date: Aug 2017 Posts: 14 Rep Power: 8 Hello everyone, Guys Please help me with the how to set the origin, e1, e2, and e3. __________________ --------------------------------------- Thanks & Regards: Shadab Mohammed

January 1, 2018, 09:59
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Tom Fahner
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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

 January 3, 2018, 02:43 #5 New Member   Shadab Mohammed Join Date: Aug 2017 Posts: 14 Rep Power: 8 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 __________________ --------------------------------------- Thanks & Regards: Shadab Mohammed