Hi CFX user, i would like to set up a time dependent pressure boundary condition on the outlet, e.g. from 0-5s, pressure=0bar; from 5-10s, pressure=1bar; from 10-15s, pressure=0bar and so on. How can this Expression (CEL) be wroten? thank you for your reply in advance.

create (or define) an user function to input your time [s] and pression [N m^-2]. Make an 1D interpolation.

Arguments Units: [s]

Results Units: [N m^-2]

Interpolation Data -> Option -> One Dimensional

Create a name.txt file and build your data (time and pression using dot as your decimal separator).

After that, choose your pression as name(t) as your boundary condition, where t is the time in [s].

Hi Rogerio, thanx for your reply. As you describled, i have defined an user function (name: function 1) in PRE. But in the outlet window i can not find the user function. How can i put the user function to outlet BC? Best regards

put "function 1(t)" in the box for the outlet. Just it. Don´t use space, in the name of the function. Use: "function1(t)"

An easier way would be just to create a CEL expression and input that into the outlet