# Divergence detected in AMG solver: k when udf loaded

 Register Blogs Members List Search Today's Posts Mark Forums Read April 20, 2015, 08:30 Divergence detected in AMG solver: k when udf loaded #1 New Member   Gromash Hellscream Join Date: Apr 2015 Posts: 2 Rep Power: 0 Hi,everyone I wanna use a udf to define the wall shear on the boundary, this udf could be loaded and initialized right, but when I begin to calculate, Fluent tells me that Divergence detected in AMG solver: k -> Increasing relaxation sweeps! When this udf unloaded, it works well, the solution is not so good though. By the way, i use VOF model here. And my code is below here, is there any problem with it? I need your help... #include #include "udf.h" #include "mem.h" #include DEFINE_PROFILE(wall_shear_x, thread, position) { real u, v, w, segm, dens,text,velo,bata; face_t f; cell_t c; Thread *t0; Domain *d; d = Get_Domain(3); int Zone_ID = 4; thread = Lookup_Thread(d, Zone_ID); begin_f_loop(f, thread) { u = F_U(f, thread); v = F_V(f, thread); w = F_W(f, thread); segm = F_P(f, thread); if (NNULLP(THREAD_STORAGE(thread, SV_DENSITY))) dens = F_R(f, thread); else { c = F_C0(f, thread); t0 = F_C0_THREAD(f, thread); dens = C_R(c, t0); } velo = sqrt(u*u + v*v + w*w); bata = -u / velo; text = segm*0.2 + 0.037731222*dens*velo*velo; F_PROFILE(f, thread, position) = text*bata; } end_f_loop(f, thread) } DEFINE_PROFILE(wall_shear_y, thread, position) { real u, v, w, segm, dens, text, velo, bata; face_t f; cell_t c; Thread *t0; Domain *d; d = Get_Domain(3); int Zone_ID = 4; thread = Lookup_Thread(d, Zone_ID); begin_f_loop(f, thread) { u = F_U(f, thread); v = F_V(f, thread); w = F_W(f, thread); segm = F_P(f, thread); if (NNULLP(THREAD_STORAGE(thread, SV_DENSITY))) dens = F_R(f, thread); else { c = F_C0(f, thread); t0 = F_C0_THREAD(f, thread); dens = C_R(c, t0); } velo = sqrt(u*u + v*v + w*w); bata = -v / velo; text = segm*0.2 + 0.037731222*dens*velo*velo; F_PROFILE(f, thread, position) = text*bata; } end_f_loop(f, thread) } DEFINE_PROFILE(wall_shear_z, thread, position) { real u, v, w, segm, dens, text, velo, bata; face_t f; cell_t c; Thread *t0; Domain *d; d = Get_Domain(3); int Zone_ID = 4; thread = Lookup_Thread(d, Zone_ID); begin_f_loop(f, thread) { u = F_U(f, thread); v = F_V(f, thread); w = F_W(f, thread); segm = F_P(f, thread); if (NNULLP(THREAD_STORAGE(thread, SV_DENSITY))) dens = F_R(f, thread); else { c = F_C0(f, thread); t0 = F_C0_THREAD(f, thread); dens = C_R(c, t0); } velo = sqrt(u*u + v*v + w*w); bata = -w / velo; text = segm*0.2 + 0.037731222*dens*velo*velo; F_PROFILE(f, thread, position) = text*bata; } end_f_loop(f, thread) }   April 20, 2015, 23:27 #2 New Member   Gromash Hellscream Join Date: Apr 2015 Posts: 2 Rep Power: 0 well, i'm so stupid, u=v=w=0 at the starting moment, how could it be calculated with a 0 denominator?    November 6, 2019, 08:43 #3
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Rahul
Join Date: Jun 2019
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Rep Power: 5 Quote:
 Originally Posted by google9002 well, i'm so stupid, u=v=w=0 at the starting moment, how could it be calculated with a 0 denominator? What changes you have made then?
I also get same type of error.   November 8, 2019, 00:34 #4 Senior Member   Alexander Join Date: Apr 2013 Posts: 2,249 Rep Power: 32  if the problem is starting point, load UDF after 1st timestep __________________ best regards ****************************** press LIKE if this message was helpful  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 siri FLUENT 8 March 12, 2018 18:08 emlejeen FLUENT 5 December 15, 2016 00:47 xinquanzhoucn FLUENT 5 July 21, 2014 05:49 n.jithin.1991 FLUENT 6 January 5, 2014 12:43 SamCanuck FLUENT 2 August 31, 2011 12:34

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