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-   -   Bc in cylindrical coordinates (http://www.cfd-online.com/Forums/openfoam-pre-processing/62079-bc-cylindrical-coordinates.html)

make July 12, 2007 11:18

I'm trying to calculate a doub
 
I'm trying to calculate a double swirler airblast nozzle using OpenFOAM as a test case. To save on calculation time I would like to ignore the swirler vanes in my grid and simple impose the swirl in the bc by using cylindrical coordinates. My question is know is it possible (by for example using the setField tool) to calculate and define the velocities for a specific boundary patch.

Thanks

cedric_duprat July 12, 2007 11:34

hi matthias, I think you ca
 
hi matthias,

I think you can try first to look for :
* rotationBC
* uniformAxialRotation
in the forum, they're piece of code written by Foamers you can try to start with.
then, ...customise them for your case, it's the most funny part, you'll see http://www.cfd-online.com/OpenFOAM_D...part/happy.gif

Cedric

olesen July 13, 2007 03:07

You might try the swirlMassFlo
 
You might try the swirlMassFlowRateInletVelocity boundary type:
http://www.cfd-online.com/OpenFOAM_D...hment_icon.gif swirlbc.tar.gz

Description
Describes an massflow normal vector boundary condition by its
magnitude as an integral over its area, with a swirl component.
The current density is used to correct the velocity.
Note: The value is positive for inward pointing vectors
Swirl is defined in RPM about the patch centre-axis according
to a right-hand rule (inwards axis).
Only useful for planar patches.

Example of the BC specification:

inlet
{
type swirlMassFlowRateInletVelocity;
massFlowRate 0.2; // [kg/s]
rpm 5000;
}

make July 13, 2007 03:40

thanks to both of you for you
 
thanks to both of you for you quick reply,

I'm going to try that over the weekend. Sounds like thats exactly what I was looking for.

have a nice weekend

make July 20, 2007 08:28

First of all Openfoam and this
 
First of all Openfoam and this communities is really great. I'm testing OpenFOAM now since a week and are really happy with it. I'm enjoying to have this kind of freedom in comparison to CFX. Its a great development environment.
Thanks to above posts I managed to write a new boundary condition where I can define my input velocities by either velocity components or flux phi, related to a cylindrical axis of rotation defined by origin and vector. I attach this perhaps somebody else find it useful. Nevertheless it is not fully tested yet! http://www.cfd-online.com/OpenFOAM_D...hment_icon.gif cylindricalCoordinateBC.tar.gz
Using this for fully 3d geometries seems to work see http://www.cfd-online.com/OpenFOAM_D...ges/1/4968.png
Now I try to calculate the same geometry as a Axi-symmetric geometry using wedge patch type boundaries. In this case my velocity profiles seems to be 2D and not related to my cylindrical axis. I also tried to use symmetryPlane type as patch type -> same. Seems I lose sight of something.
Anybody any idea?

danielle April 6, 2008 00:03

Hi, In my equation in a cyli
 
Hi,
In my equation in a cylindrical coordinate I have laplacien(A), I will solve it in Open Foam.
How can I write this term in OF ?

mcjicpm2 March 19, 2009 06:37

how to implement the files?
 
Hi

can anyone please tel me what should I do with this file in the following message?

where should I copy it? what should I do if I want to use it?

the original message has been reported by olesen a few lines above:


You might try the swirlMassFlowRateInletVelocity boundary type:
http://www.cfd-online.com/Forums/../...hment_icon.gif swirlbc.tar.gz

Description
Describes an massflow normal vector boundary condition by its
magnitude as an integral over its area, with a swirl component.
The current density is used to correct the velocity.
Note: The value is positive for inward pointing vectors
Swirl is defined in RPM about the patch centre-axis according
to a right-hand rule (inwards axis).
Only useful for planar patches.

Example of the BC specification:

inlet
{
type swirlMassFlowRateInletVelocity;
massFlowRate 0.2; // [kg/s]
rpm 5000;
}

natrask April 29, 2009 11:24

Does anyone have an alternative link to the swirlMassFlowRateInletVelocity inlet condition? The link appears to be dead.

Thanks,
Nat

kbambas May 17, 2011 11:44

Information in new boundary condition
 
I'm trying to implement a new boundary cylindrical velocity following u(r) ,what the form is U(r)=Umax ( 1- (r/d)2 ) using OpenFOAM as a test case icoFoam . I don't know how to do!so I want someone help me to giving the indications.
Thanks evrybody
.

calim_cfd August 8, 2011 06:51

Quote:

Originally Posted by kbambas (Post 307989)
I'm trying to implement a new boundary cylindrical velocity following u(r) ,what the form is U(r)=Umax ( 1- (r/d)2 ) using OpenFOAM as a test case icoFoam . I don't know how to do!so I want someone help me to giving the indications.
Thanks evrybody
.

hi there!

i'm new to op and the post seemed to be dead but u brought it up :P so here's my feeling about your doubt.. i'm not rly sure u can set that in cylindrical CS,, u could try a cartesian but regardless i'm not so sure how you'd set a user specifield field like yours... i'd have to dig a big but im out of time to spare now sry :(...but b4 u try anything..check ur problem... i guess you're trying to model a developed flow at your inlet right? cuz the solver should give you a flow with this profile like as an awnser.. plus idk if ur trying to model a transient or a SS flow...make sure you got a well posed problem b4 venturing into changing the code..

/calim


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