Turbulrnt flow past cylinder
 

Hi Foamers,

I set up the case of transient flow past circular cylinder with following conditions
Re = 3.6*10^6
Velocity = 3.6 m/s
turbulent intensity = 0.5%

I am getting an error as attached in a snapshot and also i have attached the 0 directory.

ControlDict is as follows.

[/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.2.1 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

libs
(
"libOpenFOAM.so"
"libincompressibleTurbulenceModel.so"
"libincompressibleRASModels.so"
);

application pimpleFoam;

startFrom startTime;

startTime 0;

stopAt endTime;

endTime 1000;

deltaT 0.001;

writeControl adjustableRunTime;

writeInterval 100;

purgeWrite 0;

writeFormat ascii;

writePrecision 6;

writeCompression uncompressed;

timeFormat general;

timePrecision 6;

runTimeModifiable true;

adjustTimeStep yes;

maxCo 1;

functions
{
probes
{
// Where to load it from
functionObjectLibs ( "libsampling.so" );

type probes;

// Name of the directory for probe data
name probes;

// Write at same frequency as fields
outputControl outputTime;
outputInterval 1;

// Fields to be probed
fields
(
p U
);

probeLocations
(
( -6 0 0 ) // at inlet
( 30 0 0 ) // at outlet

( 18 0 0 ) // at central block
);
}
}

// ************************************************** *********************** //]

Its a problem of your courant number as you see in your terminal picture.

your maximum courant number is set to 1 but you get some of 10^28.

It would be helpful to take a shorter write interval and have a look at some pressure peaks before the breakdown.

what's the difference between your fixed walls and walls?

greeting
pingat

Specifying Boundary Conditions in pimpleFOAM
 

Hi

Here are the boundaries specified and the case geometry and mesh are shown in this snap shot attached with this mail.

Hi
I just run the case with write interval of 0.5 but the problem remains the same as before..
No change at all...
Can you tell how to resolve this problem

Constant and system directories of the case
 

Hi
Kindly find the attached system and constant directories for reference.

you should set your write interval to a step, that you can see what is happening at time 2.07.
there you get a time step of 10^-60 and a high courant number, so maybe there is a problem in your meshing?

maybe you could post a pressure and velocity picture at that time.

Hi ,

I am running the case but one thing i ma observing that deltaT=0.001 in control dict but its displaying deltaT of the order of 10^-7 and simulation is very slow...
Why is this so ?
As per my knowledge whichever deltaT we have specified in controlDict that value has to be come on terminal box.
Can anyone clarify this please .

if there is no convergence at the given timestep, the solver trys to take a smaller step.

Hi pingat ,
What might be the reason for non convergence ????????

I also get this error from time to time, then I changed the mesh a little, the problem disappeared. I've no idea why.