Temperature at specific time steps

migit · March 10, 2011, 11:29

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

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.

March 10, 2011, 11:29	Temperature at specific time steps	#1
migit New Member England Join Date: Jul 2010 Posts: 2 Rep Power: 0	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

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March 10, 2011, 14:29		#2
singer1812 Senior Member Edmund Singer P.E. Join Date: Aug 2010 Location: Minneapolis, MN Posts: 511 Rep Power: 21	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.

March 11, 2011, 05:12		#3
migit New Member England Join Date: Jul 2010 Posts: 2 Rep Power: 0	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?

March 11, 2011, 05:38		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,893 Rep Power: 144	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.