[jignesh_thaker2007]

hi
i m using openfoam200 & i solved tutorial of LCD so i have one doubt is it possible in openfoam to give the residue limits & after achieving that limit the program will stop? if yes then plz tel me how is it possible?

i m still waiting for reply

[marupio]

Residual limits? I assume you mean the convergence criteria. These are located in the fvSolution file.

[alberto]

The "search" function is always your friend ;-)

[jignesh_thaker2007]

yes sir i know it is placed in fvsol dict. but i dont know that how to stop the programe when conversion limit cross.

like in fluent when conversion criteria satisfy then stop the program automatically but in openfoam when it reach the exit time then it stop

so i eager to know sir how can i stop my program automatically when it reaches over the conversion limits

plz reply me

yours faithfully
jignesh

[alberto]

If you specify a convergence criterion, the solver will stop automatically.

Best,

[jignesh_thaker2007]

Originally Posted by alberto

If you specify a convergence criterion, the solver will stop automatically.

Best,

ya i know but suppose in cavity tutorial tolerance is given same as conversion criteria.
so if i want to stop my program when it will go beyond my conversion criteria then what should i write in fvsol dict.

plz tel me

[Yahoo]

I am trying to solve equation

fvScalarMatrix CEqn
(
fvm::ddt(C)
+ fvm::div(phi, C)

);
CeqnResidual = CEqn.solve().initialResidual();

In case where phi is zero (i.e. no flow), my initial residuals are always high (~ 0.3). When I am forcing the solver to exit without satisfying the convergence criterion (by setting a maximum for the iterations), I see that phi is zero everywhere and C is constant, as I expect. But, I don't know why CeqnResidual is high!

[sita]

Hi all,

Thanks for all those questions and answers on convergence, they helped me a lot!

I'm aware that this thread is rather old, but my question is similar to other questions asked here, so I'll post here anyway.

At the moment I'm using interFoam for marine hydrodynamics, calm water resistance computations on ship hulls. For this type of simulations it's often necessary to apply velocity ramping at the start, which makes the simulation inherently transient. However, after this velocity ramp at start-up, the simulation should normally converge to a steady solution, which is really all I'm interested in.

Is there a way in OpenFOAM to stop a transient simulation when a steady solution is reached?

Many thanks!
Sita

[farzadmech]

Dear Alberto
My residuals are like this(see attached figure), and they do not goes down to 10e-4(or 10e-5), but my value of interest which is drag coefficient (Cd) is constant. Can I rely on my obtained results? or what should I do? do you have any suggestion?


Thanks,
Farzad

Originally Posted by alberto

Machine zero (or machine epsilon http://en.wikipedia.org/wiki/Machine_epsilon ) depends on the machine. As reference, 1.0 x 10^-12 is what I use as reference. Someone uses smaller numbers.

Best,