[Hamedhoorijani]

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

[mAlletto]

https://www.openfoam.com/documentati...tricField.html

Have a look at the functions storeoldtime und oldtime

[Hamedhoorijani]

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

[mAlletto]

Try to grep for it in the source code. I guess you will find some examples there

[geth03]

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.

[Hamedhoorijani]

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.

[Aniy]

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.