ACCESS_VIOLATION

sriah

Thsi is my UDF to use as the source of a species transportation equation.As the source term, it computs the mass fraction change rate of the third species in the secondary phase. when i run fluent,it showed ACCESS_VIOLATION error. please tell me what is wrong with it .Is the "thread "used wrong? Thanks in advance! #include "udf.h" DEFINE_SOURCE(mass_source1,c,t,dS,eqn) { Thread **t1=THREAD_SUB_THREADS(t); real source,physical_dt; physical_dt=RP_Get_Real("physical-time-step"); source=(C_YI(c,t1[1],2)-C_YI_M1(c,t1[1],2))/physical_dt; dS[eqn]=0; return source; }