Interpolate time averaged values
 

Hi!
I wonder if someone can help me, i've searched in this forum an Ansys user guide but can find a solution.

I have a problem where the flow field is hard to converge in a steady simulation but works fine when I do it transient. I then want to calculate the dispersion of a passive scalar in the field and to save computational power I want to use the "frozen" steady flow field.

Is it possible to use the time averaged field from the transient simulation to solve the transport equation.

I can save the time averaged values for post processing but how to read it into fluent?

You can freeze the velocity field by disabling the flow and any other equations you don't need.

In the GUI go to solution controls => equations and uncheck flow,etc.

This will freeze the velocity field at the current time-step (it will not use the time-averaged velocity field).

What you need to do is patch the instantaneous velocity field with the mean field. The mean field is stored as a separate variable. Unfortunately Fluent won't let you reference a builtin variable so you must create a custom field function.

Create a custom field function for each of the mean quantities:
custom-function-0 = mean_x_velocity
do this for all quantities (mean_y_velocity, mean_temperature, etc).

Then you can patch the instantaneous x-velocity, y-velocity, z-velocity to the custom function. Just make sure you patch everything and don't forget any important variables.