# problem with C_VOF and C_UDSI

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 April 13, 2004, 08:59 problem with C_VOF and C_UDSI #1 Paulina Guest   Posts: n/a Hi all, I have written an UDF,( a part of which, attached below), in order to calculate the third moment "mom3" of the distribution of the drop diameters. I would like to calculate that moment as a C_UDSI(c,t,2), which should be calculate from a volume fraction of the second phase C_VOF(c,t,1)divided by constant value 0.523. The value of the C_VOF(c,t,1) should be taken from calculation, which have been made using Eulerian approaches - ASM model in Fluent 5.5 or Mixture model in Fluent 6.1.18. DEFINE_ADJUST(usrfn,domain) { cell_t c; Thread *t; real mom3; thread_loop_c(t,domain) { begin_c_loop(c,t) { C_UDSI(c,t,2) = C_VOF(c,t,1)/0.523; mom3 = C_UDSI(c,t,2); } } } The UDF was interpreted and compiled succesfully, but the probem is that, I cann't take the values of the volume fraction of the second phase and substitude at the C_UDSI(c,t,2). And all the time I have got an error: "Segmentation violation" Does any one have a suggestion? Thanks in advance. Paulina

 April 13, 2004, 11:14 Re: problem with C_VOF and C_UDSI #2 ap Guest   Posts: n/a The proper syntax of C_VOF in FLUENT 6 is: C_VOF (cell, pt[n]) where pt is an array of pointers to threads and n is the thread index. C_UDSI is used for user-defined scalars, and the proper syntax is C_UDSI(cell, thread, name_of_scalar) See UDF manual for further info. Hi ap Arjun Jayakumar and utkunun like this.

 April 16, 2004, 05:25 Re: problem with C_VOF and C_UDSI #3 Paulina Guest   Posts: n/a Dear Ap! Thank you for your response. I have read the UDF manual, but I can't find solution to my problem still. Now I have changed my udf and after successful compiled, I got an error: "Error: Set_THREAD_Variables: wta(real), Error Object: ((constant . 0) (profile " " " ")". Below I attached two udfs, could you look at them and give me some advices? DEFINE_ADJUST(usrfn, domain) { real vof; Thread **pt; Thread *thread; mp_thread_loop_c(thread,domain,pt) { cell_t cell; begin_c_loop_int(cell,thread) { vof = C_VOF(cell,pt[1])/0.523; C_UDSI(c,t,2) = vof; } end_c_loop_int(cell,thread) } thread_loop_c (t,domain) { begin_c_loop (c,t) { mom[1] = C_UDSI(c,t,0); mom[2] = C_UDSI(c,t,1); mom[3] = C_UDSI(c,t,2); } end_c_loop (c,t) } } I also have written the another udf, but the same message of the error has appeared: DEFINE_ADJUST(usrfn, domain) { real vof; Thread *thread; Thread **pt = THREAD_SUB_THREAD(thread,1); begin_c_loop(c,pt[1]) { vof = C_VOF(c,pt[1])/0.523; C_UDSI(c,t,2) = vof; } end_c_loop(c,pt[1]) thread_loop_c (t,domain) { begin_c_loop (c,t) { mom[1] = C_UDSI(c,t,0); mom[2] = C_UDSI(c,t,1); mom[3] = C_UDSI(c,t,2); } end_c_loop (c,t) } } Thanks for all sugestions Best regards Paulina

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