CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   CFX (http://www.cfd-online.com/Forums/cfx/)
-   -   Temperature at specific time steps (http://www.cfd-online.com/Forums/cfx/85962-temperature-specific-time-steps.html)

migit March 10, 2011 11:29

Temperature at specific time steps
 
Hi all,

I am trying to get a Expression done that gives me the difference of the last 3 or 4 Temperature peaks in a transient simulation, and I want to use this expression in the Interrupt Control.

I know at what times the peaks are, so I can get the time step numbers. I can also create a script to get those values, but only after the simulation run is finished.

What I need is a expression like:
0.01 [K] > MaxT@Timestep(81) - MaxT@Timestep(61)

I know "@Timestep(81)" doesn't exist, but I am looking for something that works like that.

Basically my simulation has periodic peak points. Those peak points are settling down at a certain temperature. When this temperature at the peaks has a change of less then 0.01 [K] I want to interrupt the simulation.

Hope somebody can help me there???

Regards,
Alex
http://dl.dropbox.com/u/15545838/peaks.jpg

singer1812 March 10, 2011 14:29

CFX Expressions cant remember prior values while in solution (you can get fancy and delay updating a variable so that you can get current timestep value - previous timestep value numbers but that is about the extent you can do in CEL). You will need user fortran.

migit March 11, 2011 05:12

Thanks for the reply.

I haven't used Fortran yet, but looks like I need to get into it. Am I assuming right, that I can play with variables and manipulate the simulation process?

ghorrocks March 11, 2011 05:38

You can do pretty much anything you like with user fortran. But be warned, it is not straight forward.

If you want to implement a simple function as you describe you could do it using a separate file (maybe a cron job) which monitors the output of your monitor point and if triggered runs the cfx5stop command. I suspect this will be much easier to implement than the fortran option.


All times are GMT -4. The time now is 07:19.