{"id":381093,"date":"2024-08-29T15:37:36","date_gmt":"2024-08-29T15:37:36","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/help-parallelizing-this-udf\/"},"modified":"2026-08-19T09:04:52","modified_gmt":"2026-08-19T09:04:52","slug":"help-parallelizing-this-udf","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/help-parallelizing-this-udf\/","title":{"rendered":"help parallelizing this udf"},"content":{"rendered":"

<p>Hello, <\/p><p>I’m running a udf to calculate heat flux values along 4 boundary faces in a 2d solid domain. this is the udf<\/p><div>#include “udf.h”<\/div><div>#include “sg.h”<\/div><div> <\/div><div>DEFINE_EXECUTE_AT_END(Direct)<\/div><div>{<\/div><div>    int i, ID, zone[4] = { 4, 5, 6, 7};<\/div><div>    double ds, A_by_es, flux, DTX, DTY, Area;<\/div><div>    double H_flux[3], A[ND_ND], es[ND_ND], dr0[ND_ND];<\/div><div>    face_t f;<\/div><div>    cell_t c0;<\/div><div>    Thread* t0, * t;<\/div><div>    Domain* d = Get_Domain(1);<\/div><div>    FILE* fp;<\/div><div> <\/div><div>    fp = fopen(“Data.txt”, “a”);  \/\/ Use append mode<\/div><div>    if (fp == NULL) {<\/div><div>        Message(“Error opening file!\\n”);<\/div><div>        return;<\/div><div>    }<\/div><div> <\/div><div>    for (i = 0; i < 4; i++) {  \/\/ Loop over all zones<\/div><div>        flux = 0.0;<\/div><div>        DTX = 0.0;<\/div><div>        DTY = 0.0;<\/div><div>        Area = 0.0;<\/div><div>        ID = zone[i];<\/div><div>        t = Lookup_Thread(d, ID);<\/div><div> <\/div><div>        begin_f_loop(f, t) <\/div><div>        {<\/div><div>            BOUNDARY_FACE_GEOMETRY(f, t, A, ds, es, A_by_es, dr0);<\/div><div>            Area += NV_MAG(A);<\/div><div>            c0 = F_C0(f, t);<\/div><div>            t0 = THREAD_T0(t);<\/div><div> <\/div><div>            DTX += C_T_RG(c0, t0)[0] * es[0] * NV_MAG(A);<\/div><div>            DTY += C_T_RG(c0, t0)[1] * es[1] * NV_MAG(A);<\/div><div> <\/div><div>            flux += (C_T_RG(c0, t0)[0] * es[0] + C_T_RG(c0, t0)[1] * es[1]) * NV_MAG(A);<\/div><div>        }<\/div><div>        end_f_loop(f, t)<\/div><div> <\/div><div>        DTX \/= Area;<\/div><div>        DTY \/= Area;<\/div><div>        flux \/= Area;<\/div><div> <\/div><div>        H_flux[i] = (32 * flux);<\/div><div> <\/div><div>        fprintf(fp, “Wall %d:\\t DTX=%f\\t DTY=%f\\t heat flux=%f\\n”, ID, DTX, DTY, H_flux[i]);<\/div><div>        Message(“Wall %d:\\t DTX=%f\\t DTY=%f\\t heat flux=%f\\n”, ID, DTX, DTY, H_flux[i]);<\/div><div>    }<\/div><div> <\/div><div>    fclose(fp);<\/div><div>}<\/div><div> <\/div><div>it builds and compiled correctly, after running the calculation I get this error<\/div><div>=   BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES<br>=   RANK 0 PID 41404 RUNNING AT “xxxx”<br>=   EXIT STATUS: -1 (ffffffff)<\/div><div> <\/div><div>I think is because I’m running fluent in parallel and this code is not parallelized. I have read the udf manual but is not clear to me how to parallelized the code. Should I use PRINCIPAL_FACE_P macros of the condition #if RP_NODE, RP_HOST? <\/div><div> <\/div><div>Any advice is welcome. Thank you.<\/div><\/p>\n","protected":false},"template":"","class_list":["post-381093","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t