CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLUENT

C_VOLUME

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   May 9, 2006, 08:25
Default C_VOLUME
  #1
AdN
Guest
 
Posts: n/a
Hello

I'm trying to get the volume of each cell in my geometry. I am in 2D axisymetrique. I kno that C_VOLUME(cell, thread) give us the volume of each cell, but when I sum all my cell volume I don't have the right volume of my geometry. My geometry is a simple tube: r=0.05m and L=0.15m So the volume will be V=pi*r*r*L=1.17*10^-3 But when I use C_VOLUME I find V=1,87*10^-4!!! I don't understand why??? Could anyone help me please?

Thanks
  Reply With Quote

Old   May 9, 2006, 08:32
Default Re: C_VOLUME
  #2
AdN
Guest
 
Posts: n/a
I try to use C_VOLUME_2D but it give me the volume as if I wasn't in 2D axisymetric but only in 2D So it give me V=L*r*1=0.0075
  Reply With Quote

Old   May 9, 2006, 08:38
Default Re: C_VOLUME
  #3
Gernot
Guest
 
Posts: n/a
One possibility is that you donīt have set the right scale-factor. You can check it there :

grid / scale

  Reply With Quote

Old   May 9, 2006, 08:50
Default Re: C_VOLUME
  #4
AdN
Guest
 
Posts: n/a
Thank you. But I verify and I set the good scale. C_VOLUME work well when I'm in 2D, so my function seems to be correct. But in axisymetric it does'nt work.

  Reply With Quote

Old   May 15, 2006, 10:43
Default Re: C_VOLUME
  #5
RoM
Guest
 
Posts: n/a
C_VOLUME returns cell_volume/(2*PI) for axisymmetric.

RoM
  Reply With Quote

Old   May 15, 2006, 10:47
Default Re: C_VOLUME
  #6
AdN
Guest
 
Posts: n/a
thank you... It's work

  Reply With Quote

Old   January 21, 2013, 01:45
Default
  #7
Senior Member
 
Join Date: Nov 2009
Posts: 125
Rep Power: 7
mactech001 is on a distinguished road
Dear Gernot,

where can i check for grid/scale please?
__________________
Thank you for your kind attention.

Kind regards,
mactech001
Currently using: ANSYS v13
mactech001 is offline   Reply With Quote

Old   January 21, 2013, 02:10
Default problem in cell volume value for source term
  #8
Senior Member
 
Join Date: Nov 2009
Posts: 125
Rep Power: 7
mactech001 is on a distinguished road
Dear all,

i may have a problem in using C_VOLUME to calculate the source in my UDF application.

i've the following UDF code that attempts to apply a temperature-dependent source term to a solid cell.

#include "udf.h"
#include "mem.h"

DEFINE_SOURCE(cell_x_source,cell,thread,dS,eqn)
{
real source;
int Ro=12e-3; /*12mOhm at 20C*/
int To=20; /*temperature 20C*/
int Iphase=20; /*Arms*/

source=Iphase*Iphase*Ro*((C_T(cell,thread)-273)/To)/C_VOLUME(cell,thread);
Message("C_T output: %g\n",C_T(cell,thread));
Message("source output: %g\n",source);
Message("C_VOLUME output: %g\n",C_VOLUME(cell,thread));

return source;
}


While running 100 iterations, i observe in the Message output that the C_VOLUME of the solid cell is changing rather than keeping at a constant value as expected. why is this happening please?

The final outcome of the run was:
Error: Divergence detected in AMG solver: temperature
Error Object: #f

Then, i go into the solid cell's 'Parameter' menu (as shown attached), and verified that the volume it calculates in the output parameter is correct: 2.57e-5 [m3]. How can i use this output parameter in UDF please?

Hope to receive any comments/ideas you may have.
__________________
Thank you for your kind attention.

Kind regards,
mactech001
Currently using: ANSYS v13
Attached Images
File Type: jpg cellvolumeopparam.jpg (94.3 KB, 5 views)
__________________
Thank you for your kind attention.

Kind regards,
mactech001
Currently using: ANSYS v13
mactech001 is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 03:31.