Stopping and restarting calculations

[Michele]

Through the DT_RESTART command, restart files are saved periodically. By setting the RESTART=.TRUE. the calculation is restarted from the last saved restart file.

Is there the possibility of restarting the simulation from any saved restart file (i.e. not the last one) ?

I have problems on restarting the calculation, I guess the last saved restart file is somehow corrupted or damaged (I had a system crash).

I tried to eliminate every file related to the last restart point, including some lines from the *.smv file, but when restarting the simulation the system always looks for the last saved (and perhaps damaged) restart file.

 

Thanks

Michele

[dr_jfloyd]

restarts are overwritten each time they are saved. If you want to be
able to use an old restart you will need to rename it or move it to
another directory before the next restart is written.

[Michele]

A *.restart file is generated for each mesh, and are large files.

Once the simulation is completed, are they still necessary (for some visualization or data capture) or can I delete them from the disk?

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[TimoK]

Yes, the restart files are large. If you are happy with
the calculation and do not want to continue it (e.g., by
increasing the T_END), then you do not need the
restart files anymore (= delete is OK).

TimoK

[Michele]

That's a good point.

If a restart file is present, by indicating RESTART=.TRUE. in the FDS file one can continue the simulation extending the T_END.

On the other side this means that if DT_RESTART is greater that T_END thare is no way to extent the simulation (by increasing the T_END) once the calculation is finished.

Good to know. Thanks a lot

 

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[Adam Pakonski]

Stupid question but how do you actually restart a simulation that has stopped? What do you write into the command line to restart?

Thank you in advance,

Adam

[Lukas A.]

Dear Adam,

see

6.4.5 Special Topic: Stopping and Restarting Calculations

in the user guide. You do not have to change anything in the command line.

Best,
Lukas

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[Adam Pakonski]

Thanks Lukas, but i read through that section several times before posting but it's still not clear to me. I must be suffering from some mild cognitive impairment! I can see a large .restart file but when i execute fds again, the simulation just starts again from time 0.00s again rather than the 300+ second time when the simulation was interrupted.
I am running an MPI simulation with multiple computers but i gather that shouldn't have any influence.

Appreciative of your reply,
Adam

[Dave McGill]

Adam,

It sounds like you forgot to add, "RESTART=.TRUE." to the &MISC line.

Dave

[Adam Pakonski]

Thanks Dave!
I think i went astray as i use Pyrosim to generate the fds file and then run the fds file in mpi from the command line. I could see that the restart files were being generated so couldn't understand why Pyrosim wouldn't also generate the necessary commands to allow the restart but upon closer inspection given your guidance it all makes sense now. When reading Sect 6.4.5 in the user guide this wasn't very apparent to me, although it does make sense in hindsight, but for the beginner a little unclear.


Thanks for your help!
Adam