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How to access previous time

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Old   December 13, 2014, 04:52
Default How to access previous time
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Dear All,

I'd like to know how to declare the previous time and access the previous time folder including 0 within my original library.
I know the current time and the current/previous time step can be obtained as follows, but don't for the previous time step "tp".

----------------------------------------------
const Time& time;

// current Time and timeStep
scalar t = time.value();
scalar dt = time.deltaTValue();

// old Time
scalar tp = ?????
scalar dtp = time.deltaT0Value();

// time step number (i.e., time index)
Info << "Time Step Index: " << time.timeIndex() << endl;
---------------------------------------------

Please let me know any way to the "tp"

Sincerely,
waku2005
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Old   December 16, 2014, 09:40
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This would also be interesting to me. My simulations are very dynamic and often become instable, which forces me to reduce the courant number temporarily to avoid unphysical results. Since these results are sometimes detectable (for example by extreme changes in min/max temperature), it would be nice if we could step back one time step, decrease the courant number and calculate again starting from the previous step.
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Old   December 16, 2014, 19:39
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My objective is to calculate moment and force vectors dynamically from field values at the previous time step, within my original solidMeshMotionFunctions developing for using in such a pimpleDyMFoam solver.

In the pimpleDyMSolver(may also be in the other DyM solvers), after a time stepping, mesh.update() was called before new p and U were calculated. If the mesh motion was prescribed using omega(rad/s) defined in the dynamicMeshDict, there's no problem.

But for my simulation, mesh motion (i.e., eulerAngles of mesh rotation) should be numerically defined by using the moment and forces those previous U and p. That's why I should access the previous time step values of the field values (NOT the previous output data!).

Any comments and suggestions were highly appreciated !

Thanks in advance,
waku2005
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Old   December 16, 2014, 20:06
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Wmmm..., I'd like to know at first,
1) U.oldTime() is automatically stored ?
2) U.oldTime() is the U of the previous time step, not the previous outputted U in a time folder ?

Sorry for my primitive questions.
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