# A fatal signal (segmentation violation)

 Register Blogs Members List Search Today's Posts Mark Forums Read February 18, 2011, 09:17 A fatal signal (segmentation violation) #1 New Member   sutthinan Join Date: Feb 2011 Posts: 9 Rep Power: 14 Hi everyone, I need to control the geometry of boundary in function of pressure in fluent by using the UDF in deform function, but fluent show massage that "A fatal signal (segmentation violation)", I really don't know about this error, this is my UDF #include "udf.h" DEFINE_GEOM(deform, domain, dt, position) { Thread *t; face_t f; real x[ND_ND]; real NV_VEC (A); real ho=0.000001, hc, def; real presur,xx; int max; int i,j; if (!Data_Valid_P ()) return; i=0.; begin_f_loop (f, t) { F_CENTROID(x,f,t); xx[i]=x; presur[i]=F_P(f, t); i=i+1; max=i; } end_f_loop (f, t) i=0.; j=0.; begin_f_loop (f, t) { for(i = 0; i < max;i++) { def=(xx[j+1]-xx[j])*presur[j]*ln(fabs((xx[i+1]+xx[i])/2.-xx[j]*fabs((xx[i-1]+xx[i])/2.-xx[j])); } hc=def/(2.*3.14); position=ho+xx[j]*xx[j]/2.+hc; j=j+1; } end_f_loop (f, t) return position; } Many thanks seucj likes this.   February 18, 2011, 10:07 #2 Senior Member   Join Date: Nov 2009 Posts: 411 Rep Power: 18 Probably your vectors are smaller than the total number of faces from your mesh. Do a grid->check to see how many faces do you have and let me know. Do   February 18, 2011, 17:57 #3 New Member   sutthinan Join Date: Feb 2011 Posts: 9 Rep Power: 14 Hi Dohander, My gird has the data as following; Level Cells Faces Nodes Partitions 0 64902 98278 33377 1 1 cell zone, 6 face zones. Thanks you so much for your suggestion. Sutthinan   February 18, 2011, 19:45 #4 Senior Member   Join Date: Nov 2009 Posts: 411 Rep Power: 18 OK, Check if the total numbers of faces (not zones) is less than 1000. I think this is why you have the memory error, specifically here: real presur,xx;   February 19, 2011, 01:57 #5 New Member   sutthinan Join Date: Feb 2011 Posts: 9 Rep Power: 14 Thank you for your advices, and I wonder that if I need to use the presure for calculating. Does which one appropriate between C_P(c,t) and F_P(f, t) ? (because both of them, I can get the same pressure)    February 19, 2011, 10:23 #6 Senior Member   Join Date: Nov 2009 Posts: 411 Rep Power: 18 One is for the pressure at the center of a cell and one for the pressure at a face of a cell. Try changing this line: real presur,xx; to real presur,xx; It should get rid of the memory violation error, at least I hope so. Do   March 16, 2011, 18:35 #7
New Member

Chun-Liang Wu
Join Date: May 2010
Posts: 2
Rep Power: 0 what is the face thread t in the face loop? The pointer t is not initialized or assigned a valid value, which absolutely returns you a "segmentation fault" error.

Quote:
 Originally Posted by sutthinan Hi everyone, I need to control the geometry of boundary in function of pressure in fluent by using the UDF in deform function, but fluent show massage that "A fatal signal (segmentation violation)", I really don't know about this error, this is my UDF #include "udf.h" DEFINE_GEOM(deform, domain, dt, position) { Thread *t; face_t f; real x[ND_ND]; real NV_VEC (A); real ho=0.000001, hc, def; real presur,xx; int max; int i,j; if (!Data_Valid_P ()) return; i=0.; begin_f_loop (f, t) { F_CENTROID(x,f,t); xx[i]=x; presur[i]=F_P(f, t); i=i+1; max=i; } end_f_loop (f, t) i=0.; j=0.; begin_f_loop (f, t) { for(i = 0; i < max;i++) { def=(xx[j+1]-xx[j])*presur[j]*ln(fabs((xx[i+1]+xx[i])/2.-xx[j]*fabs((xx[i-1]+xx[i])/2.-xx[j])); } hc=def/(2.*3.14); position=ho+xx[j]*xx[j]/2.+hc; j=j+1; } end_f_loop (f, t) return position; } Many thanks  Thread Tools Search this Thread Show Printable Version Email this Page Search this Thread: Advanced Search Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode 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 OffTrackbacks are Off Pingbacks are On Refbacks are On Forum Rules Similar Threads Thread Thread Starter Forum Replies Last Post Conan FLUENT 9 December 20, 2019 12:31 Ahlo CFX 1 August 3, 2009 11:05 wasan FLUENT 0 December 23, 2008 11:37 Jungfeng FLUENT 0 October 8, 2007 11:05 CFD user CFX 3 November 25, 2002 15:16

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