# Time average value of a UDS

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 April 17, 2004, 08:01 Time average value of a UDS #1 ap Guest   Posts: n/a I need to calculate the time average value of a User Defined Scalar in my simulation. Is there a macro which does this? Hi and thanks ap

 April 17, 2004, 11:44 Re: Time average value of a UDS #2 Ajay Guest   Posts: n/a FLUENT has this option "Data sampling for Time statistics" when you do an unsteady calculation in the iterate panel that might help. I havent used it before. -Ajay

 April 17, 2004, 15:10 Re: Time average value of a UDS #3 ap Guest   Posts: n/a Thank you. But that option just enable statistics for a small set of variables, and not for a UDS. Hi ap

 April 18, 2004, 07:46 Re: Time average value of a UDS #4 thomas Guest   Posts: n/a hello, The Data sampling for Time statistics should not be very difficult to compute via UDF. Just need 2 variables: - A: one to store your UDS value at each time step. - B: a second one to store the number of time step (= to the number of UDS values store in the first variable). - your time average is A/B That can be done using a DEFINE_EXECUTE_AT_END (with an UDMI inside) and the command C -> '=+' for each variable. Post-treating the UDMI will give you your UDS time average. Hope this help, Thomas

 April 18, 2004, 15:25 Re: Time average value of a UDS #5 ap Guest   Posts: n/a Thank you Thomas. I thought to that method, but I have to use a really small time step (0.0001 s) to simulate a long time (1 to 2 minutes), so, if I sum all values I think I'll obtain an overflow. Any idea? Hi ap

 April 19, 2004, 02:56 Re: Time average value of a UDS #6 thomas Guest   Posts: n/a Maybe do your averaging every 10 time step or so.