Learning Forum

[lzfneu]

Hi all,

I intend to load heat generate rate to source term, which is in a cylinder shape.

I try to write profile in r-phi-z format and the attachment is my transient profile file. The field I set is r, angle, z, respectively. Please help to check if I am right? and how to set the source term in cell zone conditions in cylinder coordinate.

Thank you very much in advance.

test.txt

[Rob]

Source terms are set via DEFINE_SOURCE or expressions, and (I think) are limited to x, y and z coordinates.

[lzfneu]

Thanks for your reply.
The heat generate rate of source term in my problem is discrete values and is in cylindral coordinate. I want to consult you is there a method to perform this kind of heat transfer calculation in fluent.
I have to find a method to import discrete values of heat generate rate which is in cylindral coordinate to source term so that I could do the next step water cooling calculation.
Any suggestions or help will be appreciated, and thank you in advance.

[Rob]

Heat transfer calcs, yes, they're fairly routine.
Using polar coordinates in code however isn't as we add sources based on position (x, y & z) as w, r and axial are relative. So, you'll need to convert the data in some way. If the data is being read to a UDF then you can convert the data as it's read in, or do the conversion externally then read the x, y & z position and it's attached data.

[lzfneu]

Thanks for your suggestions. I prefer your suggestion to do the conversion externally then read the x, y & z position and it's attached data.
I want to confirm that if I am right: I intend to write the externally conversed data to profile and then read to my source term. The field in profile I use should be x,y,z and the attached data (heat generate rate).
Thank you very much for your help.

[Rob]

Profiles are for surfaces. For source terms you'll need to read & assign the data into the source term so you'll need the file read functions and (possibly) some interpolation routines to add in values assuming the mesh & points don't line up.

[lzfneu]

Dear Rob Thanks for your reply.
I want to import the heat generation rate (W/cm3) to the source term according to different x, y, z coordinations.
For example, the heat generation is 1000W/cm3 in the location x=1.11cm, y=2.22cm, z=3.33cm; and is 2000W/cm3 in the location x=8.88cm, y=9.99cm, z=10.10cm; 3000W/cm3 in the location x=20.22cm, y=30.33cm, z=40.44cm;
In order to achieve that, I write the source term as follows:
#include "udf.h"
DEFINE_SOURCE(test, c, t, dS, eqn)
{
real x[ND_ND];
real a, b, c, source;
C_CENTROID(x, c, t);
a=x[0]; b=x[1]; c=x[2]; // x,y,z coordinate
if(a==1.11 && b==2.22 && c==3.33) {source=1000;}
if(a==8.88 && b==9.99 && c==10.10) {source=2000;}
if(a==20.22 && b==30.33 && c==40.44) {source=3000;}
dS[eqn]=0;
return source;
}
Is it right?
And is there any convinent method to use if there are many x, y, z coordiantes and heat generations, thank you very much in advance.

[Rob]

Sort of. You need to give the source a volume rather than a position so it'll be
if( a>1.0 && a<1.2 && b.....
Remember source terms are per m3 so be careful with the definitions.