This function is prediction for erosion of cavitation. I am writing udf for fluent. To this point udf is working. How can I sum C_UDMI? I want to sum C_UDMI (erosion) for all time steps of calculation. Now it only gives me result of the last time step/iteration. Here is current udf: Code: /******************************************************************** UDF for calculating something and printing it to console window at the end of the current iteration or time step *********************************************************************/ #include "udf.h" /*************************************************************************************************************/ /*definiramo novo spremenljivko C_UDMI(c,t,0), ki se zapise le ob koncu casovnega koraka in je enaka C_STRAIN_RATE_MAG(c,t);*/ /*ne pozabi it v define-user defined-memory in dat prosto mesto!!!*/ DEFINE_EXECUTE_AT_END(execute_at_end) { Domain *d; Thread *t; cell_t c; face_t f; d = Get_Domain(1); /* mixture domain if multiphase */ thread_loop_c (t,d) { if (FLUID_THREAD_P(t)) { begin_c_loop(c,t) { if (8.97*pow(1.1,2)*sqrt(C_P(c,t)/0.5542) > 118.745878036397) C_UDMI(c,t,0) = 26.7*pow(10,-5)/1484*(8.97*pow(1.1,2)*sqrt(C_P(c,t)/0.5542)-sqrt((200000000/998.2)*(1-(pow((1+200/300),-1/7))))); else if (8.97*pow(1.1,2)*sqrt(C_P(c,t)/0.5542) <= 118.745878036397) C_UDMI(c,t,0) = 0.; } end_c_loop(c,t) } } } Thank you for helping Gašper