CFD Online Discussion Forums

CFD Online Discussion Forums (
-   CFX (
-   -   CEL expression for controlling an energy source with respect to time (

rglithro December 6, 2011 08:07

CEL expression for controlling an energy source with respect to time
Hello all
I would like to be able to control an energy source in my transient simulation with respect to time e.g. t=0 on at t=2 off at t=20 on at t=22 off etc. The simulation is for testing conformal cooling channel designs for injection moulding tools with the energy source simulating the injection phase of the moulding cycle.
From reading tutorials on the CFX Expression Language I understand it should be possible to do this using CEL and I have read a couple of tutorials on creating feedback loops to control temperature but what I donít understand is how to write an expression for a boundary condition or with respect to time. I am not a programmer so this is all pretty new to me; any help would be greatly appreciated.
Software: ANSYS Workbench V13
So to summarise my question
1) Does anyone know of an example/tutorial of an expression which is written for turning an energy source on or off with respect to time step
2) Can anyone help me out with creating an example of the code I need to achieve the above

Additional info: I currently have the above problem setup as 3 separate analysis; a) steady-state (for initial conditions of the fluid flow in the cooling channel) b) transient 2s (heating) c) transient 18s (cooling time) but I would like to be able to run it multiple times to simulate multiple moulding cycles all in the same analysis.

ghorrocks December 6, 2011 19:45

This is just a straight forward CEL expression. No programming needed. Use the mod function to define a periodic function and link the CEL expression to your boundary condition.

rglithro December 7, 2011 12:28

Sorted, thank you for pointing me in the right direction.

All times are GMT -4. The time now is 22:54.