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-   -   starting Transient analysis from the previous time step. (http://www.cfd-online.com/Forums/cfx/115256-starting-transient-analysis-previous-time-step.html)

kmgraju March 27, 2013 03:30

starting Transient analysis from the previous time step.
 
Dear all

I have completed transient analysis for 2 sec. I feel that the solution is not converged so, I want to increase to another 2 or 3 s. Is it possible to do the analysis from the previous time step? If so kindly help me how to so the setup in the solver.I need your opinion .

Thank you

Lance March 27, 2013 04:03

In the solver:
initial values specification/file name: specify your last .res or full .trn file
check "continue history from"

jthiakz March 27, 2013 14:55

Step1: Open the final result in CFX pre and check the initial time setting, If it is automatic no probs other wise change it to automatic and write def file

Step 2: In solver manger locate the the new def file and check the initialization and also enable continue run from history" , now you check and update us...

kmgraju April 3, 2013 13:11

I have completed transient analysis first 2 s then 1 s then 1 s . but I could not able to load all the results. I found only the last time step results.how can i load all the results.

Thank you

cycleodyssey April 3, 2013 22:01

Hiya,
CFXPre defaults to keeping the last time step only usually, this reduces file size as if you save for every step soon transient runs take up a lot of space...
To save steps you need to run again but change the setup in CFXPre. In CFXPre click on output control --> Trn Results which gives you options for output frequency for every time step, or intervals etc. Run simulation again and it will save trn results for the output frequency selected. If you want to save residuals you need to select them in CFXPre at Output Control -> Results -> select Output Equation Residuals text box.

Another way is to monitor points of interest, like Cl or Cd or whatever you are interested in, then you can export this in solver by right clicking on solver window --> export to csv. Residuals are included here as well...

Cheers

kmgraju April 4, 2013 00:45

Quote:

Originally Posted by cycleodyssey (Post 418204)
Hiya,
CFXPre defaults to keeping the last time step only usually, this reduces file size as if you save for every step soon transient runs take up a lot of space...
To save steps you need to run again but change the setup in CFXPre. In CFXPre click on output control --> Trn Results which gives you options for output frequency for every time step, or intervals etc. Run simulation again and it will save trn results for the output frequency selected. If you want to save residuals you need to select them in CFXPre at Output Control -> Results -> select Output Equation Residuals text box.

Another way is to monitor points of interest, like Cl or Cd or whatever you are interested in, then you can export this in solver by right clicking on solver window --> export to csv. Residuals are included here as well...

Cheers


Thank you
so much
I have another question to clarify. I use total time 4s. each cycle ends in 1 s
I have given each time step of 0.005s ( total time step 800) . But my question is , to write the transient results from 3rd cycle on words provided the solver has to run for 1st and second cycles normally. But the transient results should write from 3rd cycle . Please help me how it is possible.

If I skip the cycles will the solution accuracy affected?

Is there any way to reduce the solution time for the same time steps (400 time steps) and it is for 3rd cycle and 4th cycles ?

Thank you


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