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time independence study

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Old   December 2, 2022, 04:07
Default time independence study
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naji
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Hi guys
I'm doing a time independence study
i have 4 time steps and i did the simulation and defined a report definition for the parameter but after ending the simulation i realized that reports weren't saved,is there any other way to compare the results except plotting based on time for time study? i have no data to compare(except case and data of every simulation) and solution time is a lot
if anyone has an idea i would appreciate
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Old   March 7, 2023, 04:15
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Nilotpal Dhar
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How are you defining the parameter? In the controlDict as functions?
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Old   March 7, 2023, 12:52
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Quote:
Originally Posted by aiden_1995 View Post
Hi guys
I'm doing a time independence study
i have 4 time steps and i did the simulation and defined a report definition for the parameter but after ending the simulation i realized that reports weren't saved,is there any other way to compare the results except plotting based on time for time study? i have no data to compare(except case and data of every simulation) and solution time is a lot
if anyone has an idea i would appreciate
It depends on the simulation you are preforming. If the setup is steady state, or transient but approaching steady state, you can compare final numbers from each case.

For example, assuming you are looking at an airfoil and your chosen parameter is the drag coefficient. You can determine the ending coefficient from each simulation and compare them against each other. By comparison I mean looking at the relative percent change between each mesh. Once the change is below 1%-5% (depending on you simulation, tolerance, etc.) you should be independent.

If, however, the simulation is transient (moving wall, changing boundary condition, etc.) your critical parameter will likely not be a single number, but a transient plot or profile. In this case there's unfortunately no way to recover the transient data if you did not export it.

If you can provide more detail on your problem I can help you determine an adequate parameter to investigate.
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