CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Fluent UDF and Scheme Programming

CX_Find_Cell_With_Point: problem

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

Like Tree3Likes
  • 1 Post By psc3
  • 1 Post By blackmask
  • 1 Post By deluge

Reply
 
LinkBack Thread Tools Display Modes
Old   May 12, 2010, 17:11
Default CX_Find_Cell_With_Point: problem
  #1
Member
 
Francesco Capuano
Join Date: May 2010
Posts: 78
Rep Power: 7
francesco_capuano is on a distinguished road
Hi everyone,
I've got a problem with the function CX_Find_Cell_With_Point, which I've found right in this forum (it is not mentioned in the UDF manual): you give it the coordinates of the point, it gives you back the cell index in which the point is. The example given by the user Gearboy was:

#include "udf.h"
DEFINE_ON_DEMAND(find_cell)
{
cell_t c;
Thread *t;
CX_Cell_Id cx_cell;
real NV_VEC(pt);
real c_centroid[ND_ND];
NV_D(pt, =, 0.5, 0.3, 0.2); //coordinate of your specified location,it must be in the domain coordinate range
CX_Start_ND_Point_Search();
cx_cell=*CX_Find_Cell_With_Point(pt);
CX_End_ND_Point_Search();
c=RP_CELL(&cx_cell); //the right cell number
t = RP_THREAD(&cx_cell); // the thread
C_CENTROID(c_centroid,c,t);
Message0("coordinate of the specified point: x=%g,y=%g,z=%g\n",pt[0],pt[1],pt[2]);
Message0("coordinate of the cell found: x=%g,y=%g,z=%g\n",c_centroid[0],c_centroid[1],c_centroid[2]);
}

The problem is: if I use this function for a single point, or for a loop of points in a flat-plate mesh, it works perfectly; if I use this function inside a loop of points for any other case, even very simple (like an airfoil), Fluent simply goes off after a while (during the elaboration), despite all the points in the loop are in the domain coordinate range and, apparently, there are no other problems with the case and the rest of the function. It seems like a memory limit is reached, or something like that. I'm quite new to Fluent and UDFs world, so I really don't know what to do, I really appreciate any suggestion.
Thanks in advance!
francesco_capuano is offline   Reply With Quote

Old   May 13, 2010, 14:36
Default
  #2
Member
 
Francesco Capuano
Join Date: May 2010
Posts: 78
Rep Power: 7
francesco_capuano is on a distinguished road
I precise that after some seconds of elaboration Fluent gives ACCESS VIOLATION error... help me please!
francesco_capuano is offline   Reply With Quote

Old   May 15, 2010, 08:28
Default
  #3
New Member
 
Join Date: Nov 2009
Posts: 8
Rep Power: 7
psc3 is on a distinguished road
try to replace real NV_VEC(pt);

with

float NV_VEC(pt);

I had a problem with this UDF and that change solved it...

Pedro
mm.abdollahzadeh likes this.

Last edited by psc3; May 15, 2010 at 13:39.
psc3 is offline   Reply With Quote

Old   May 16, 2010, 15:51
Default
  #4
Member
 
Francesco Capuano
Join Date: May 2010
Posts: 78
Rep Power: 7
francesco_capuano is on a distinguished road
Thank you Pedro for your suggestion, that's a good idea, but it doesn't work for my case.
Anyway, I've fixed the bug: I realized that the problem for the function was to analyze the points belonging to the boundary face (probably it is unable to judge whether they belong to the computational domain or not), so excluding that points from the loop the UDF works fine.
francesco_capuano is offline   Reply With Quote

Old   May 17, 2010, 07:30
Default
  #5
Senior Member
 
dmoroian's Avatar
 
Dragos
Join Date: Mar 2009
Posts: 647
Rep Power: 11
dmoroian is on a distinguished road
Are you sure it works ok?
This instruction:
Code:
cx_cell=*CX_Find_Cell_With_Point(pt);
doesn't look right. It should give you a syntax error. At first glance I would write it as:
Code:
cx_cell = CX_Find_Cell_With_Point(pt);
dmoroian is offline   Reply With Quote

Old   May 17, 2010, 09:55
Default
  #6
Member
 
Francesco Capuano
Join Date: May 2010
Posts: 78
Rep Power: 7
francesco_capuano is on a distinguished road
Thanks for helping, dmoroian, but the function CX_Find_Cell_With_Point(pt) requires the asterisk. As I said, the problem does not regard the syntax, but the point you ask the function to analyze. It seems not to work fine for the boundary points...
francesco_capuano is offline   Reply With Quote

Old   August 26, 2013, 15:08
Default
  #7
New Member
 
Join Date: Aug 2013
Posts: 3
Rep Power: 3
deluge is on a distinguished road
Hi,

This line
Code:
cx_cell = CX_Find_Cell_With_Point(pt);
or this one, it doesn't matter which one
Code:
cx_cell=*CX_Find_Cell_With_Point(pt);
always gives me the error:
error C2440: '=' : cannot convert from 'int' to 'CX_Cell_Id'
Does anybody know how to avoid it?
deluge is offline   Reply With Quote

Old   August 27, 2013, 01:17
Default
  #8
Senior Member
 
Join Date: Aug 2011
Posts: 315
Rep Power: 11
blackmask will become famous soon enough
You do not provide the full warning/error message, do you? It could be misleading. There should be some warning messages tell 'implicit declaration of function CX_Find_Cell_With_Point'. Please include the right header file,
Code:
#include "cxiface.h"
for fluent version 6.x

The interface for this function changed in version 14 so I do not discuss the header file in this version because the above code does not work any way.
mm.abdollahzadeh likes this.
blackmask is offline   Reply With Quote

Old   August 27, 2013, 03:37
Default
  #9
New Member
 
Join Date: Aug 2013
Posts: 3
Rep Power: 3
deluge is on a distinguished road
Thank you blackmask,

I'm using the latest version, that's 14.5.7. There is no more cxiface.h and a grep search revealed there is no more CX_Find_Cell_With_Point either.

Has anybody an idea how the corresponding commands are called in 14.x.x?
deluge is offline   Reply With Quote

Old   August 27, 2013, 05:11
Default
  #10
Senior Member
 
dmoroian's Avatar
 
Dragos
Join Date: Mar 2009
Posts: 647
Rep Power: 11
dmoroian is on a distinguished road
Yes it is in
Code:
fluent/fluent14.5.7/cortex/src/cxndsearch.h
dmoroian is offline   Reply With Quote

Old   August 28, 2013, 04:21
Default
  #11
New Member
 
Join Date: Aug 2013
Posts: 3
Rep Power: 3
deluge is on a distinguished road
Thanks a lot for that!

But the syntax seems to be a bit more complex than before.

Code:
FLUENT_EXPORT ND_Search *CX_Start_ND_Point_Search(ND_Search *, cxboolean do_domain, int t_id);
FLUENT_EXPORT CX_Cell_Id *CX_Find_Cell_With_Point(ND_Search *, double v[3], double time);
FLUENT_EXPORT ND_Search *CX_End_ND_Point_Search(ND_Search *);
The functions require more inputs.
Code:
CX_Start_ND_Point_Search();
cx_cell=*CX_Find_Cell_With_Point(pt);
CX_End_ND_Point_Search()
doesn't work because of a lack of inputs. Does anybody have an example for that? I find these input datatypes very confusing.
mm.abdollahzadeh likes this.
deluge is offline   Reply With Quote

Old   April 5, 2014, 21:35
Default
  #12
New Member
 
Jason
Join Date: Jul 2013
Posts: 1
Rep Power: 0
KingSt is on a distinguished road
Quote:
Originally Posted by deluge View Post
Thanks a lot for that!

But the syntax seems to be a bit more complex than before.

Code:
FLUENT_EXPORT ND_Search *CX_Start_ND_Point_Search(ND_Search *, cxboolean do_domain, int t_id);
FLUENT_EXPORT CX_Cell_Id *CX_Find_Cell_With_Point(ND_Search *, double v[3], double time);
FLUENT_EXPORT ND_Search *CX_End_ND_Point_Search(ND_Search *);
The functions require more inputs.
Code:
CX_Start_ND_Point_Search();
cx_cell=*CX_Find_Cell_With_Point(pt);
CX_End_ND_Point_Search()
doesn't work because of a lack of inputs. Does anybody have an example for that? I find these input datatypes very confusing.
Hi deluge,

Did you figure out this problem??? I am suffering the exactly same problem as yours. Could you guys give any suggestion? Appreciate!
KingSt is offline   Reply With Quote

Old   June 24, 2014, 13:14
Default
  #13
New Member
 
Garvit Goel
Join Date: May 2014
Posts: 11
Rep Power: 3
garvitgoel is on a distinguished road
Quote:
Originally Posted by deluge View Post
Thanks a lot for that!

But the syntax seems to be a bit more complex than before.

Code:
FLUENT_EXPORT ND_Search *CX_Start_ND_Point_Search(ND_Search *, cxboolean do_domain, int t_id);
FLUENT_EXPORT CX_Cell_Id *CX_Find_Cell_With_Point(ND_Search *, double v[3], double time);
FLUENT_EXPORT ND_Search *CX_End_ND_Point_Search(ND_Search *);
The functions require more inputs.
Code:
CX_Start_ND_Point_Search();
cx_cell=*CX_Find_Cell_With_Point(pt);
CX_End_ND_Point_Search()
doesn't work because of a lack of inputs. Does anybody have an example for that? I find these input datatypes very confusing.
can somebody please explain how to use these search functions.
I cant under stand what t_id and v[3] and time are.
garvitgoel 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


Similar Threads
Thread Thread Starter Forum Replies Last Post
UDF compiling problem Wouter Fluent UDF and Scheme Programming 6 June 6, 2012 04:43
Incoherent problem table in hollow-fiber spinning Gianni FLUENT 0 April 5, 2008 10:33
natural convection problem for a CHT problem Se-Hee CFX 2 June 10, 2007 06:29
Adiabatic and Rotating wall (Convection problem) ParodDav CFX 5 April 29, 2007 19:13
Is this problem well posed? Thomas P. Abraham Main CFD Forum 5 September 8, 1999 14:52


All times are GMT -4. The time now is 18:06.