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July 2, 2010, 07:12 
3D axissymmetric problem

#1 
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hello,
i have to solve a axissymmetric 3Dproblem (cylinder)  magnetohydrodynamic problem coupled with boussinesqapproximation. Is there any way to solve it in OpenFoam without cylindrical coordinates and without the wedge condition, only with a special boundary condition!? So  maybe  through a constant azimuthal (theta direction) component!? But how could i implement such a condition? Thanks a lot. noramat 

July 2, 2010, 07:30 

#2 
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i'm also a starter at OF and i'm not familiar with magnetohydrodynamics in OF but generally 2D Simulations can be done with wedges
if you want to define a new boundary condition you have to programm and compile it, have a look at: http://www.tfd.chalmers.se/~hani/kurser/OS_CFD_2007/ http://www.tfd.chalmers.se/~hani/kur...yCondition.pdf Implement boundary condition i hope this helps Last edited by marcbest; July 2, 2010 at 07:49. 

July 2, 2010, 07:45 

#3  
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maddalena
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Hi,
Quote:
Hope this helps. cheers, mad 

July 13, 2010, 16:07 

#4 
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thanks for your answers!
now i have another question to wedgetype .. so  wedgetype is used for 2daxisymmetric problems. Does the wedgetype imply, that all quantities are independent of the angular/azimuthal component phi (constant in phi direction) and that the angular/azimuthal velocity u_phi is zero? If the last fact is not true (u_phi = 0), how could i implement that? Maybe through a special boundary condition again? thanks a lot again! noramat 

July 13, 2010, 16:43 

#5  
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maddalena
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Hi Noramat,
I am not sure I understand your question correctly but... Wedge type is 2D. OF does the trick of using a 3D mesh to solve a 2D case, but in reality all your properties are (and remain) constant along the third dimension, which is not solved indeed. Thus I would say yes: Quote:
mad 

July 14, 2010, 05:22 

#6 
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thanks again!
that's one answer i need but now i'm still not sure because of the other fact.. so i have to solve a axisymmetric problem (zylinder) with the condition that the angular velocity u_phi is zero. but is it realised by wedgetype? thanks! normat 

July 14, 2010, 05:53 

#7 
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maddalena
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Hi Noramat,
is U_phi the angular velocity? If it is, than u_phi will be zero, since the angular direction is not solved by OF. On the other hand, if you are interested on an angular direction, than your problem is not 2D. Indeed, you have two geometrical directions (radial and axial) + one phisical direction (circonferential, or angular, as you like), thus the problem is 3D. In that case, the wedge bc cannot be applied and you should use a cyclic instead. hope that this makes things clearer. cheers, mad 

July 14, 2010, 05:58 

#8 
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thanks very much!


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