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How many time-steps are included in each .dat file for Fluent transient simulations?

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Old   March 30, 2015, 17:36
Default How many time-steps are included in each .dat file for Fluent transient simulations?
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nm
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I just discovered the hard way that fluent .dat written using the autosave function after particular intervals (every 40 iterations here) store different number of time steps.

This is quite annoying.

For instance results written at 480 iterations contain times 320, 360,400, 440 and 480.

Results written, at 360 only have 360 and 320.

Results written at 320 have, 320,280 and 240?

Why are the .dat files so inconsistent? I noticed this only after I imported them to CFDpost.

Thanks for reading.
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Old   April 2, 2015, 09:45
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I figured out a few other ways to track and write down the transient results but this still bothers me.

Anyone got any idea what determines the number of time steps in a fluent dat file written during calculation?
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Old   April 3, 2015, 01:01
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I did not think it was ever possible for Fluent to save data from old time-steps in a single .dat file since the .dat file should contain only data of the current state.

If you are running transient simulation with 1st order backward differencing, then naturally the .dat file will contain data at the current time-step plus the previous time-step.

If you are running 2nd order, then the .dat file should contain the current time-step (n), the previous time-step (n-1), and the one before the previous time-step (n-2).

It shouldn't contain n-40 time-steps. I don't know how that happens.
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Old   April 3, 2015, 09:45
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Right? I am confused as well. I was using Tecplot all my life but recently had to switch to CFDpost. So post-proc of transient simulations is a pain.

Anyway this is what I get when I import ONE timestep dat. Different timestep dat files have different number of timesteps stored and it's completely random.

temp1.PNG
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Old   September 20, 2016, 15:27
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did you find solution to this problem?
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data file, fluent 14.5.7, transient analysis

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