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-   -   FOAM WARNING at time (https://www.cfd-online.com/Forums/openfoam/114985-foam-warning-time.html)

 vahidzanganeh March 21, 2013 04:51

FOAM WARNING at time

hi foamers,

This warning is encountered during implementation. And the solution is diverging.:confused:
//--------------
Courant Number mean: 4.89667e-05 max: 0.488398
deltaT = 1.06092e-56
--> FOAM Warning :
From function Time::operator++()
in file db/Time/Time.C at line 1010
Increased the timePrecision from 519 to 520 to distinguish between timeNames at time 0.209868
Time = 0.209868454511289076469537917546404059976339340209 9609375
//--------------------------------
How can I solved this warning.
best regards

 nimasam March 22, 2013 01:48

hi dear vahid
deltaT = 1.06092e-56
is so little, so you should decrease your time step in controlDict to remove this warning.
how much time do you want to simulate? (1 sec, 1 min, ....)
however this little time step shows, some where your solver works wrong! i recommend to check up your BC or your implantation :) because with this small time step :), for and ordinary time it would take so so long time :)

 Lieven March 22, 2013 02:38

Indeed, this could be an indication that something is wrong with the BC like nimasam says. But it might also be that you started with a too big Courant number (~too big time step), this can create instabilities with extremely small time steps as a result. And last, it could also be caused by badly chosen initial conditions. Taking a small time step at the beginning of the run could correct for this.

Cheers,

L

 vahidzanganeh March 22, 2013 03:45

hi
I'm modeling combustion with reactingFoam solver . i used to start the combustion from energy source in the energy equation at Specific time. After applying the energy source comes up warning.
//--------------
energySource1
{
type scalarExplicitSource;
active true;
timeStart 0.2;
duration 0.05;
selectionMode points;
points
(
(0.067 0.00035 -0.01)
);

scalarExplicitSourceCoeffs
{
volumeMode absolute;
injectionRate
{
hs 2;
}
}
}
//-----------------------------------
best reagard

 nimasam March 22, 2013 16:00

i suggest to add source in several points instead of one point!, it may solves problem

 vahidzanganeh March 23, 2013 07:35