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-   -   How to store transient data with various timestep? (http://www.cfd-online.com/Forums/cfx/21948-how-store-transient-data-various-timestep.html)

Oliver December 16, 2005 00:33

How to store transient data with various timestep?
 
Hi,

I've a problem storing transient data. I run the transient simulation from 0 to 10 second with time step of 0.00001 second but I only want to save data as follows:

1) from 0 to 1 second with 0.0001second time intervals

2) from 1 to 2 second with 0.001second time intervals

3) from 2 to 3 second with 0.1 second time intervals

4) from 3 to 10 second with 1 second time intervals

How can I specify time intervals in Pre (under Output Control menu)? I've both 5.7.1 and 10 at different machines.

In 5.7.1, I can either select a fixed time intervals or put a time list....However, I have different time intervals here. Inserting 1000+++ time value in the time list is exhuasting....Any better way of doing this? If it's not possible, please also let me know....

Thanks for your help. Oliver.

Rui December 16, 2005 08:24

Re: How to store transient data with various times
 
Hi,

As far as I know it isn't possible. The only way I see to do that is by creating 4 different simulations, and starting simulation 2 with the .res file from simulation 1, and so on.

Regards,

Rui

Jianping December 16, 2005 18:01

Re: How to store transient data with various times
 
Hi, Oliver

If you input 10000*0.0001, 1000*0.001, 10*0.1, 7*1 as your time step, you should be able to get what you want.

Regards!

Jianping

Oliver December 18, 2005 20:29

Re: How to store transient data with various times
 
"If you input 10000*0.0001, 1000*0.001, 10*0.1, 7*1 as your time step, you should be able to get what you want."

Thanks for your help but how could the solver know the time when the time step start to change if you specify this way?

e.g. 1000*0.001 time interval is supposed to start at t=1 second while 7*1 time interval will start at t=3second....

Jianping December 18, 2005 20:56

Re: How to store transient data with various times
 
Hi,

If you feel confused about this, you can simply test it by run a case with time step as '2*0.1, 2*1'.

Regards!

Jianping


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