[mohammadizadi]

Hi
I want draw graph(pressure coeff vs psition y) in any timestep
but I have no idea

[fluid23]

You will need to create a series of derived parts > probe > points. Then setup a solution history for the variable(s) you want to reference at any given time step. After that you can configure an XY plot to use the solution view of your history that you can roll back to any time step.

I suggest you review the help material. There are instructions and even an example that does this sort of thing. You just have to read how it all works, far too much to explain here...

[fluid23]

You could take the simple route and ignore the solution history nonsense by saving images of the plot at each time step. Here you just need to setup you XY plot and change the update option to 'time step', toggle 'save to file' and assign an output directory. If you go this route, I would put a plot annotation that says what time step you are looking at.