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-   -   Axisymmetric swirl - angular velocity for UDF (http://www.cfd-online.com/Forums/fluent-udf/94610-axisymmetric-swirl-angular-velocity-udf.html)

NTSbike November 21, 2011 07:05

Axisymmetric swirl - angular velocity for UDF
 
hi everyone

i'm making a momentum field (tangential - like lorenz force in a magnetic case) to spin/rotate liquid metal in a cylindrical space. I need the angular velocity of every cell for my UDF. In 3D i can get it from velocity components and radius (radius is generated from coordinates).

but what is c_u(), c_v(), c_w() in axisymmetric swirl 2d. how can I get the angular velocity in rad/sec (or tangential velocity).

thanks
cheers
TS

vahid.najafi July 27, 2012 07:46

plz help me!!!
 
Hi dear Tsaba Nagy.
I need to use 2D geometry for my solver and see axisymmetric swirl 2d in your comment!!!please tell me how can I do this for my project?

NTSbike July 27, 2012 07:50

please write, what you want :) since the post I developed a lot in these stuff. I hope I can help you ;)

vahid.najafi July 27, 2012 09:29

details
 
2 Attachment(s)
dear Tsaba Nagy.
I want to use 2Daxisymmetric for openFoam,and for this reason used makeAxialmesh and coolapse to make wedge type for boundary.
I make it,but my result after run is not correct and differrent with 3Dmodel.other friends tell me ,I must be use axisymmetric swirl 2d .....
if my work in modelling 2DAxisymetric is not correct please tell me???
Thanks a lot.

NTSbike July 27, 2012 09:43

the 2d axs. swirl solver is needed when there are swirling velocities too in the system you wanna model. In this case I'm not sure, that there is this type of velocity inside but worth to try.

forget this wedge cut shape model. for 3D draw the full media. for 2D the half of the meridional cut is enough - as you drew on the bottom of the first paper. set axis boundary condition here, others can be simple in/otlets, walls, etc.

if the inlet of the pressure is homogenous on the surface, the 2D is totally enoug to see what's happening inside.

did I understood well, what you want? :)

vahid.najafi July 27, 2012 10:13

answer
 
Thanks for your answer.
but i know my drew on the bottom of the first paper is correct!!!!but i dont know how can i do this???in openFoam 2D, conveted in 3D!!!

NTSbike July 27, 2012 10:35

I just work with FLUENT, so I can help justwith it now :/

Robb13 June 30, 2015 08:09

Tangential velocity in 2D axisymmetric flow with swirl
 
I am currently working on the modelling of droplets in swirling, turbulent, pipe flow. I use a UDF to model the evaporation of the droplets, however, there is a problem with the particle and fluid velocities.

The fluid swirl-velocity is an output parameter of the calculations. However, I do not know how to use this parameter in Fluent. It is not the same as the cell velocity C_W(c,t), since that value is (null) in the calculations.

Thanks in advance!

NTSbike July 2, 2015 07:23

Maybe a too stupid/basic question, but are you pointing at the correct thread level for C_W, like


Thread *t_l = THREAD_SUB_THREAD(t,0);
real parameter =C_W(c,t_l);



It would be great to get more info about your case... :)


Cheers


Quote:

Originally Posted by Robb13 (Post 552688)
I am currently working on the modelling of droplets in swirling, turbulent, pipe flow. I use a UDF to model the evaporation of the droplets, however, there is a problem with the particle and fluid velocities.

The fluid swirl-velocity is an output parameter of the calculations. However, I do not know how to use this parameter in Fluent. It is not the same as the cell velocity C_W(c,t), since that value is (null) in the calculations.

Thanks in advance!


Robb13 July 2, 2015 07:53

Currently, I am using it on the following way:

DEFINE_DPM_TIMESTEP(droplets_laws,p,dt_dpm)
{

... Other lines...

real W_C
cell_t c = P_CELL(p);
Thread *t = P_CELL_THREAD(p);
C_CENTROID(x,c,t);
W_C = C_W(c,t);

... Other lines...

}


However, I found out that C_WSWIRL(c,t) does return a value instead of C_W(c,t).


For my case, I model the evaporation of droplets using an inhouse-UDF.
In this routine, I use the difference between the particle velocity and the carrier phase velocity at particle position to calculate the particle Reynolds number.
For that purpose, the cell center velocity C_U(c,t) is interpolated to the particle position by means of the gradients C_DUDX(c,t) (with DUDZ, DYDZ and DWDZ zero by definition).
However, I found out that I also can use the inteprolated values from Fluent directly, so the problem is probably solved by making use of the following line:

W_C = p->cphase.V[3];

azna September 21, 2015 15:03

Hi,

i need to run my case using 2D axisymmetric swirl, in Fluent. I was wondering that how can I define the swirl angle? I was wondering that do you know any tutorials that has used axisymmetric swirl.

Thanks a lot

Quote:

Originally Posted by NTSbike (Post 373964)
I just work with FLUENT, so I can help justwith it now :/



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