Questions about unsteady restart simulation.

Amber0922 · June 27, 2023, 00:44

Hi,
I have run an unsteady simulation, and to save the storage space, I set " OUTPUT_WRT_FREQ= 100, 100, 100 ", so the restart flow date is 100, 200, and so on. At the same time, I set "WINDOW_START_ITER = 100 " to get the time average variables.
But when I want to restart the solution, I set "RESTART_SOL= YES" and "RESTART_ITER=102", I hope it can read the 100 flow. but it said "Unable to open SU2 restart file restart_flow_00101.dat". Unfortunately, I didn't restore the 101 date, my storage is 100, 200 and ....
So, what can I do to restart the simulation from the 100 or any other flow which I saved. Any help is important for me, thanks in advance.

pcg · June 27, 2023, 19:17

The best you can do is to do one time step with first order in time, and then restart again with second order in time.
The second best is to make a copy of the file you have.
You are probably using an old version because we made this more friendly recently and now the solver outputs two files when necessary.

Amber0922 · June 27, 2023, 22:32

Hi,Pedro
My version is 7.5.1, I'm not sure if it has the feature that you said. But it exactly saved the restart_flow_100, restart_flow_199, restart_flow_200 and so on. So should I set the restart begin at 198? Or run the simulation again?
Best wishes.

Amber0922 · June 27, 2023, 23:32

And another bewilderment is that when I set RESTART_ITER=99, it seems to find the 97 flow and restart with it. In my opinion, it should find the 100 and run that. So , does the restart simulation begin the iteration at the 97, if I set RESTART_ITER=99?

pcg · June 28, 2023, 11:09

If you start at iteration "n" you need files "n-1" and "n-2"

Amber0922 · June 28, 2023, 23:24

I realized that I had misunderstood the difference between steady and unsteady restart simulations, thanks to your patience, everything has been resolved.

Amber0922 · June 28, 2023, 23:37

I realized that I had misunderstood the difference between steady and unsteady restart simulations, thanks to your patience, everything has been resolved.

June 27, 2023, 00:44	Questions about unsteady restart simulation.	#1
Amber0922 Member Zhang Join Date: Mar 2023 Posts: 72 Rep Power: 3	Hi, I have run an unsteady simulation, and to save the storage space, I set " OUTPUT_WRT_FREQ= 100, 100, 100 ", so the restart flow date is 100, 200, and so on. At the same time, I set "WINDOW_START_ITER = 100 " to get the time average variables. But when I want to restart the solution, I set "RESTART_SOL= YES" and "RESTART_ITER=102", I hope it can read the 100 flow. but it said "Unable to open SU2 restart file restart_flow_00101.dat". Unfortunately, I didn't restore the 101 date, my storage is 100, 200 and .... So, what can I do to restart the simulation from the 100 or any other flow which I saved. Any help is important for me, thanks in advance.

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June 27, 2023, 19:17		#2
pcg Senior Member Pedro Gomes Join Date: Dec 2017 Posts: 466 Rep Power: 14	The best you can do is to do one time step with first order in time, and then restart again with second order in time. The second best is to make a copy of the file you have. You are probably using an old version because we made this more friendly recently and now the solver outputs two files when necessary.

June 27, 2023, 22:32		#3
Amber0922 Member Zhang Join Date: Mar 2023 Posts: 72 Rep Power: 3	Hi,Pedro My version is 7.5.1, I'm not sure if it has the feature that you said. But it exactly saved the restart_flow_100, restart_flow_199, restart_flow_200 and so on. So should I set the restart begin at 198? Or run the simulation again? Best wishes.

June 27, 2023, 23:32		#4
Amber0922 Member Zhang Join Date: Mar 2023 Posts: 72 Rep Power: 3	And another bewilderment is that when I set RESTART_ITER=99, it seems to find the 97 flow and restart with it. In my opinion, it should find the 100 and run that. So , does the restart simulation begin the iteration at the 97, if I set RESTART_ITER=99?

June 28, 2023, 11:09		#5
pcg Senior Member Pedro Gomes Join Date: Dec 2017 Posts: 466 Rep Power: 14	If you start at iteration "n" you need files "n-1" and "n-2"

June 28, 2023, 23:24		#6
Amber0922 Member Zhang Join Date: Mar 2023 Posts: 72 Rep Power: 3	I realized that I had misunderstood the difference between steady and unsteady restart simulations, thanks to your patience, everything has been resolved.

June 28, 2023, 23:37		#7
Amber0922 Member Zhang Join Date: Mar 2023 Posts: 72 Rep Power: 3	I realized that I had misunderstood the difference between steady and unsteady restart simulations, thanks to your patience, everything has been resolved.