The macro is what you put in your photo. C_STORAGE_RYou will write the equation as it is ... c and t are cell and thread at outlet. and delta_time_sampled = Sampling Interval;And by the way, if you are interested only in average temperature, why don't you make mass average and monitor it in the solution. You don't need UDF for thathttps://forum.ansys.com/discussion/comment/106154#Comment_106154

Is this enough to calculate the average temperature at the outlet? Or I have to define something else too.n