Use another simulation or run for initial conditions

It would be really handy if I could use previous results as initial conditions, the reason is my simulation crashes at 0.35s and I need to do solver alterations to get it past this point. However to get it to 0.35 it takes a day to get to this point so would be handy to just start at say 0.33s and run from there? obviously it would need to be the same mesh but could specify a start from time, a simulation and run and a time step to initialise from. This would save me a lot of sim time :blush:

I think you can do it in open foam (Iā€™m no open foam expert I just red it on CFD online).

Kind regards,
Darren Lynch

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Thereā€™s a lot of value in being able to put previous results as initial conditions for other reasons like faster convergence when running from a turbulence model to another. I believe this will be coming eventually to SimScale.

Hello @1318980 and @oscarcorripio,

I agree with the value of such options! I would consider them rather as two different features. What you mentioned Darren is what we call a concept of run pausing/continuation, which should allow you to pause jobs, re-start them and also continue them once they are finished by defining a new simulation time limit. When doing this some options of the simulation setup should be changeable as you mentioned e.g. numeric settings.
What you mentioned @oscarcorripio would be more powerful, but also a bit more complex as it should be possible to initialize for example the velocity and pressure field in the fluid domains in a conjugate heat transfer simulation with previous results of an incompressible flow that you might have done as a first simple approach to the problem you are facing. This can be very interesting for boundary conditions as well as you might want to define a pressure boundary condition in a solid mechanics simulation based on a previous flow simulation. As the concept is so powerful and helpful we are already investing in these connectivity topics, but it will certainly take some time. Stay tuned though!

Best Alex

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Hi Alex,

I am running a transient simulation. I would like to continue the finished simulation by defining a new simulation time limit. However when I open completed run, ā€˜Simulation Controlā€™ is non editable.

Can you or anyone help me on this?

Hi @pajadhav20

I donā€™t think it is possible at current stage and this feature may be added in the future. I would like to invite sir @jousefm to give some details on the progress/plans on introducing this feature request.

Thanks
Ani

Hi @pajadhav20!

You can extend the maximum iterations and maximum runtime and continue the run from the latest time step. You can have a look at this video to see how it works: Run Continuation. Please feel free to share a screenshot of your problem as well.

Best,

Jousef

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Hi Sir

I think that @pajadhav20 is asking whether we can continue our simulation from the last timestep with different delta T in transient simulation cases or not?? If he meant to say simulation end time by ā€œtime limitā€ then yes you can extend your total simulation time.
I would myself like to know whether Delta T can be changed when we continue our simulation(in transient cases)?

Thanks
Ani

Hi @jousefm ,
I am simulating transient simulation where I am monitoring pressure drop vs time. For ease of simulation I am defining some end time with adaptable time step. I have completed First run with 0.0005 s time step and 1 second as end time. Now I want to continue same run with 0.001 time step and 10 second as end time.
Instead of starting newly, Can I continue same run with changing these parameters as I do not want to initialize with default setting ?

Thank you,
Pramod

Hi @pajadhav20 @anirudh2821998 @jousefm,

You cannot currently continue a transient run, therefore the answer about altering dt is unfortunately no. I believe the ultimate goal of run continuation will support that use case., just not right now.

Best,
Darren

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