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How to access the results of previous time-steps during solution? |
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#1 |
New Member
Hamed Hoorijani
Join Date: May 2019
Location: Gent, Belgium
Posts: 22
Rep Power: 7 ![]() |
Hi everyone,
I'm researching recurrence CFD and wanted to know does the OpenFOAM keeps the Fields and Scalar results of previous time steps during the solution or not? and If so how I can get access to each of these matrices that contain results during simulation? In another word, What I need to know is, if the solver is at the 1000th time step of solution, is there a way to have access to the results of the 999 time steps before it? I'll be grateful if you could guide me. Many thanks |
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#2 |
Senior Member
Michael Alletto
Join Date: Jun 2018
Location: Bremen
Posts: 616
Rep Power: 16 ![]() |
https://www.openfoam.com/documentati...tricField.html
Have a look at the functions storeoldtime und oldtime |
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#3 |
New Member
Hamed Hoorijani
Join Date: May 2019
Location: Gent, Belgium
Posts: 22
Rep Power: 7 ![]() |
Thanks a lot dear Micheal for your response.
That was helpful actually. but I'm having a hard time finding how to use these functions of GeometricField class. how should I call them in the solver? Thanks |
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#4 |
Senior Member
Michael Alletto
Join Date: Jun 2018
Location: Bremen
Posts: 616
Rep Power: 16 ![]() |
Try to grep for it in the source code. I guess you will find some examples there
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#5 |
Senior Member
Join Date: Dec 2019
Location: Cologne, Germany
Posts: 365
Rep Power: 8 ![]() |
if you want to access the 999 previous timesteps out of 1000, you need to store them! as far as i know, openfoam saves the previous timestep values automatically, it would be insane to store every timestep, what kind of memory do you need for that when the problem is large?
i read your other question and i think you want to use a former timestep as initial value for the current time without interrupting the simulation. if you already know which time step you will take as initial value than you could write a Allrun script that does it for you. |
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#6 |
New Member
Hamed Hoorijani
Join Date: May 2019
Location: Gent, Belgium
Posts: 22
Rep Power: 7 ![]() |
Hi, dear geth03,
Thanks a lot for your answer. yeah at first I was looking for a way to store the values but as you mentioned, it's not a proper method to do so and it's not computationally efficient. Now I want to do exactly as you said. I want to continue the solution of a problem until it reaches a time for instance time step (i) then if a set of conditions were met by the results then resume the solution with initial values of a previous time step for example time step (i-200). I need to implement this in a solver's code. is this possible? and if so I'll appreciate if you could guide me. |
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#7 |
New Member
Join Date: Feb 2021
Posts: 2
Rep Power: 0 ![]() |
Hi, try <surfaceScalarField>.OldTimes().boundaryField()[myPatchID]
Add these two code lines: const surfaceScalarField& phi = this->db().objectRegistry::lookupObject<surfaceScalarFi eld>("phi"); const label myPatchID = this->patch().boundaryMesh().findPatchID(patchName); Then: phi.nOldTimes().boundaryField()[myPatchID] It returns the flow rate field from last iteration at user-defined patch. You can use this code to get to temperature field and so on. |
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Tags |
openfoam, programing, solver development |
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