Time step size with adaptive time steps

Racing_34 · April 12, 2013, 14:56

Hi everyone,
i'm trying to run a transient simulation with adaptive time step length.
I have an expression in which i need the time step size, but i can't figure out how i can get that information. I tried both with dtstep and with "Time Step Size" but, even if in cfx-pre they're written in italic (which means i'm calling a built-in expression), in cfx-post i have this message "ERROR
The following unrecognized name was referenced: Time Step Size." and cfx can't calculate my expression.

So, how can i get the information i need?

Thank you

ghorrocks · April 13, 2013, 08:57

dtstep is available in the solver but not the post-processor. It should work fine in the solver. So I presume you are using it in the post processor. Why do you need it in the post processor?

Racing_34 · April 14, 2013, 11:15

Quote:

Originally Posted by ghorrocks

dtstep is available in the solver but not the post-processor. It should work fine in the solver. So I presume you are using it in the post processor. Why do you need it in the post processor?

i'm modeling the saturation of a dual scale porous media, saturation is defined as 'accumulated saturation'+constant*t step size so i need to visualize it because it's one of my work's output

thanks

ghorrocks · April 14, 2013, 19:32

I cannot see a way of doing this in the post processor. You can do this in the solver by defining an additional variable and a source term. Alternately you can export the raw data and do the intgeration in another package (excel, matlab, python whatever you like).

April 12, 2013, 14:56	Time step size with adaptive time steps	#1
Racing_34 New Member Join Date: Dec 2010 Posts: 3 Rep Power: 16	Hi everyone, i'm trying to run a transient simulation with adaptive time step length. I have an expression in which i need the time step size, but i can't figure out how i can get that information. I tried both with dtstep and with "Time Step Size" but, even if in cfx-pre they're written in italic (which means i'm calling a built-in expression), in cfx-post i have this message "ERROR The following unrecognized name was referenced: Time Step Size." and cfx can't calculate my expression. So, how can i get the information i need? Thank you

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April 13, 2013, 08:57		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,872 Rep Power: 144	dtstep is available in the solver but not the post-processor. It should work fine in the solver. So I presume you are using it in the post processor. Why do you need it in the post processor?

April 14, 2013, 19:32		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,872 Rep Power: 144	I cannot see a way of doing this in the post processor. You can do this in the solver by defining an additional variable and a source term. Alternately you can export the raw data and do the intgeration in another package (excel, matlab, python whatever you like).