CFD Online Discussion Forums - OpenFOAM

Check yPlus without reconstructing in parallel runs

maysmech — Thu, 09 Sep 2010 08:15:24 GMT

Dear Foamers,:)

i want check yPlus before reconstructing decomposed solutions in OF1.7 because of its time consuming process. is it possible?

A question on adaptive remeshing or mesh deformation for handling object motions

daveatstyacht — Thu, 09 Sep 2010 01:06:36 GMT

Hi all,
I have been trying to run interDyMFoam on a model with a very fine mesh near the surface of a boat hull. Unfortunately, the motion of the hull due to heave and trim causes the small cells near the hull to collapse and results in a divergence after a mere two hundredths of a second. I have traditionally used an inverseDistance diffusivity and this has worked fine for a coarse mesh, but I am now trying to better capture the boundary layer with a finer mesh and have run into trouble since. I have decided that there are two possible solutions to these problems.

Solution 1: Create a mesh that is static relative to the hull in a region surrounding the hull where the mesh is finest and deform coarser cells farther away. This seems like the preferred approach since it saves the time consuming process of remeshing, but I have not managed to create a region of cells that will be recognized in the arguments of BC and the dynamicMeshDict. I have tried creating a cell set but have not been able to get it to modify the constants files (boundary and faceZones in particular). Does anyone know the set of commands to take a cell set and make it into a useful cell region for this problem? Also does anyone know if the region needs BC in the /0 folder and if so what the pointDisplacement BC should be to move with the hull?

Solution 2: Use mesh deformation as it is but then remesh when the cell deformation gets severe enough. This remeshing posses two problems to me. First I need to define the remeshing based on the magnitude of cellDisplacement, but the remesher is looking for a VolScalarField such as alpha1 or p. Does someone know if it is possible to do this at run time or will this require modifying the code? Secondly, I have tried running with both dynamic mesh options active (inverseDistance diffusivity and then refinemesh based on alpha1 to keep to what know works in the tutorials). Unfortunately, it wont run at all in parallel because it is looking at both the global and processor cell levels and see a different number of cells and aborts. When I tried to run it one processor I get the following error:

FOAM FATAL ERROR:
Only call if constructed with history capability

From function hexRef8::getSplitPoints()
in file polyTopoChance/polyTopoChange/hexRef8.C at line 4884.

FOAM aborting

In any case any insight into either approach (particularly the first since it looks more promising) would be greatly appreciated.

Regards,
-Dave

Problem with turbulence model

akonduri — Wed, 08 Sep 2010 20:47:06 GMT

Hi,

I am trying to do LES of flow past a square cylinder. For LES model, I am using locDynOneEqEddy. When I run the code, I get the following error. Can someone tell me want is going wrong?

============================
ERROR:
=============================

Create time

Create mesh for time = 0

Reading field p

Reading field U

Reading/calculating face flux field phi

Selecting incompressible transport model Newtonian
Selecting turbulence model type LESModel
Selecting LES turbulence model locDynOneEqEddy
#0 Foam::error::printStack(Foam::Ostream&) in "/home/akonduri/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/home/akonduri/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#2 __restore_rt at sigaction.c:0
#3 __kernel_standard at interp.c:0
#4 Foam::pow(Foam::Field&, Foam::UList const&, double const&) in "/home/akonduri/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#5 Foam::tmp > Foam::pow(Foam::GeometricField const&, Foam::dimensioned const&) in "/home/akonduri/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libincompressibleRASModels.so"
#6 Foam::incompressible::LESModels::locDynOneEqEddy:: ck(Foam::GeometricField, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField const&) const in "/home/akonduri/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libincompressibleLESModels.so"
#7 Foam::incompressible::LESModels::locDynOneEqEddy:: updateSubGridScaleFields(Foam::GeometricField, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField const&) in "/home/akonduri/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libincompressibleLESModels.so"
#8 Foam::incompressible::LESModels::locDynOneEqEddy:: locDynOneEqEddy(Foam::GeometricField, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField const&, Foam::transportModel&) in "/home/akonduri/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libincompressibleLESModels.so"
#9 Foam::incompressible::LESModel::adddictionaryConst ructorToTable::New(Foam::GeometricField, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField const&, Foam::transportModel&) in "/home/akonduri/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libincompressibleLESModels.so"
#10 Foam::incompressible::LESModel::New(Foam::Geometri cField, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField const&, Foam::transportModel&) in "/home/akonduri/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libincompressibleLESModels.so"
#11 Foam::incompressible::turbulenceModel::addturbulen ceModelConstructorToTable::NewturbulenceModel(Foam::GeometricField, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField const&, Foam::transportModel&) in "/home/akonduri/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libincompressibleLESModels.so"
#12 Foam::incompressible::turbulenceModel::New(Foam::G eometricField, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField const&, Foam::transportModel&) in "/home/akonduri/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libincompressibleTurbulenceModel.so"
#13 main in "/home/akonduri/OpenFOAM/akonduri-1.6/applications/bin/linux64GccDPOpt/pisoFoamAdi"
#14 __libc_start_main in "/lib64/libc.so.6"
#15 Foam::regIOobject::writeObject(Foam::IOstream::str eamFormat, Foam::IOstream::versionNumber, Foam::IOstream::compressionType) const in "/home/akonduri/OpenFOAM/akonduri-1.6/applications/bin/linux64GccDPOpt/pisoFoamAdi"

multiple patches per surface

hyperion — Wed, 08 Sep 2010 18:03:05 GMT

Hi there - could anyone give me or direct me to information on how to apply different patches to a surface on a solid created with netgen? I have seen that this can be done by specifying points on a block using blockMesh, but I don't know how to do something like this for a mesh created externally.

Thanks

System time overhead in OF

askjak — Wed, 08 Sep 2010 10:42:03 GMT

Hi all,

I have noticed that on our cluster that openfoam have a very different cpu usage compared to other cfd codes.

In OF a large fraction of the time is spend in system cpu time compared to user cpu time. Other cfd codes we have had our hands on spend almost 100% of the time in user cpu.

I have made a small case based on the angledDuct case with 178000 cells using simpleFoam. The case was constructed so no IO was performed.

In serial more than 30% of the time is spend in system time. Is this an overhead due to the dynamic memory allocation in OF?

Attachment 4644

When running the case in parallel (2 nodes) the system time CPU time fraction drops to a few percent which is difficult for me to understand.

Attachment 4645

Can anyone explain the apparent serial overhead?

Best regards,
Ask

Attached Images

	simpleFoam_job.jpg (59.8 KB)
	simpleFoam_job2.jpg (59.5 KB)

sonicFOAM for an airfoil error

inginer — Tue, 07 Sep 2010 17:26:26 GMT

Hello,

I'm trying to do a sonicFoam case in OF 1.7.0 with a mesh imported from fluent. it is an airfoil 2d with M=0.8.
after building the case i try to run it and i receive the following error

openfoam@linux-bkii:~/OpenFOAM/openfoam-1.7.0/run/projects/cmyairfoil> sonicFoam
/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.7.0 |
| \\ / A nd | Web:www.OpenFOAM.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
Build : 1.7.0-21131bcbd876
Exec : sonicFoam
Date : Sep 07 2010
Time : 16:10:12
Host : linux-bkii
PID : 8245
Case : /home/openfoam/OpenFOAM/openfoam-1.7.0/run/projects/cmyairfoil
nProcs : 1
SigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create mesh for time = 0

Reading thermophysical properties

Selecting thermodynamics package ePsiThermo>>>>
Reading field U

Reading/calculating face flux field phi

Creating turbulence model

Selecting turbulence model type RASModel
Selecting RAS turbulence model SpalartAllmaras
SpalartAllmarasCoeffs
{
sigmaNut 0.66666;
kappa 0.41;
Prt 1;
Cb1 0.1355;
Cb2 0.622;
Cw2 0.3;
Cw3 2;
Cv1 7.1;
Cv2 5;
}

Starting time loop

Time = 2.13e-09

Courant Number mean: 5.01425e-06 max: 0.00279144
#0 Foam::error::printStack(Foam::Ostream&) in "/home/openfoam/OpenFOAM/OpenFOAM-1.7.0/lib/linuxGccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/home/openfoam/OpenFOAM/OpenFOAM-1.7.0/lib/linuxGccDPOpt/libOpenFOAM.so"
#2 Uninterpreted:
#3 Foam::divide(Foam::Field&, Foam::UList const&, Foam::UList const&) in "/home/openfoam/OpenFOAM/OpenFOAM-1.7.0/lib/linuxGccDPOpt/libOpenFOAM.so"
#4 Foam::operator/(Foam::UList const&, Foam::UList const&) in "/home/openfoam/OpenFOAM/OpenFOAM-1.7.0/lib/linuxGccDPOpt/libOpenFOAM.so"
#5 Foam::diagonalSolver::solve(Foam::Field&, Foam::Field const&, unsigned char) const in "/home/openfoam/OpenFOAM/OpenFOAM-1.7.0/lib/linuxGccDPOpt/libOpenFOAM.so"
#6 Foam::fvMatrix::solve(Foam::dictionary const&) in "/home/openfoam/OpenFOAM/OpenFOAM-1.7.0/lib/linuxGccDPOpt/libfiniteVolume.so"
#7 Foam::lduMatrix::solverPerformance Foam::solve(Foam::tmp > const&) in "/home/openfoam/OpenFOAM/openfoam-1.7.0/applications/bin/linuxGccDPOpt/sonicFoam"
#8 main in "/home/openfoam/OpenFOAM/openfoam-1.7.0/applications/bin/linuxGccDPOpt/sonicFoam"
#9 __libc_start_main in "/lib/libc.so.6"
#10 _start at /usr/src/packages/BUILD/glibc-2.10.1/csu/../sysdeps/i386/elf/start.S:122
Floating point exception
openfoam@linux-bkii:~/OpenFOAM/openfoam-1.7.0/run/projects/cmyairfoil>

anybody receive a similar error? what i did wrong???
Thk you

Ovidiu

Defining B.C. --> velocity profile

maysmech — Tue, 07 Sep 2010 16:52:03 GMT

Dear Foamers,

I need to define Driver and Seegmiller velocity inlet profile for backward facing step.

How can i write it in 0/U flie?

MPI barrier inside OpenFoam

matteoL — Tue, 07 Sep 2010 15:12:00 GMT

Hello,
when running in parallel, for some reasons I have some actions that have to be done only by the master core and I would like the other partitions to wait until the master has finished.
(I call those action doing:
If (Pstream::master()){ ...} )

I think the solution in a general c++ code using MPI would be to add a line like:
MPI_BARRIER(MPI_COMM_WORLD)

Is there an already implemented function in OF available?
OR,
how could i get acces to the MPI class/function/settings?

Thank you very much,
best regards,
Matteo

Sliding Interface in OpenFoam?

lordvon — Mon, 06 Sep 2010 14:01:48 GMT

The following is part of my correspondence with 'enquiries@opencfd.co.uk':

"...In which case it is likely you will need to perform these calculations using a
sliding-interface. This functionality is not yet part of OpenFOAM but we have a
detailed plat to implement it and are looking for sponsors; would you be
interested in sponsoring this work?"

(I was asking him if modeling a 2D simulation with a rotor and stator is possible)

But I do a little bit of searching on these forums and it appears OpenFoam is capable of implementing sliding interfaces:

http://www.cfd-online.com/Forums/ope...e-problem.html
(and others, including a pdf written by Dr. Jasak)

In short:
Are sliding interfaces buit into OpenFoam?
How can I implement it? Is there an example file I can learn from and build off of?

Thanks for your time.

Steady state Multi species non-reactive model

Hrushi — Mon, 06 Sep 2010 12:36:21 GMT

hi,
I am new to OpenFOAM. I want to develop steady state multi species non reactive model. How to go about it?

Do I need to modify the simpleFoam code to introduce the species equation? If yes, how to do it? Correct me, if I am wrong.

Is there any otherway to do this?

Hrushikesh

transient Simulation with porous media

Chrisi1984 — Mon, 06 Sep 2010 08:45:41 GMT

Hi,

is there a transient solver which can model porous medias in OpenFOAM ?

Also there is a file "porousZones" in folder constant of the tutorial for the solver rhoPimpleFoam (OF 1.6), for me it seems as if the solver would not include the darcy law, right?

Can some one give me advise how to implement the darcy law like it is done in rhoPorousSimpleFoam (implicit).

Are anywhere still existing some transient solvers for porous media?

Best ragards Chrisi

SonicFoam simulation probleme

bruxellois — Sat, 04 Sep 2010 21:22:02 GMT

Dear Foamers!

I'm trying to simulate the exhaust of a muzzle, my mesh and my boundary conditions are ok (transient boundary condition (time-depended) ), i'm using sonicFoam (with perfect gas).

the simulation do not give any result (0 iteration all the time).

You can find my case directory here

http://www.4shared.com/file/hpAUp6tE/test64tar.html

Any help please.

Alex

Attached Files

0.tar.gz (1.6 KB)

permanent magnet motor project

bl�bussen — Sat, 04 Sep 2010 09:48:46 GMT

I will develop a model for a permanent magnet motor in steps and I wonder if this can be done in OpenFoam. This is what I want to do:

Step 1) Create 2D geometry of rotor and calculate stress and strain due to speed of rotation, i.e a mechanics problem with centrifugal forces.

Step 2) Add 2D stator and solve electromagnetic problem, either with current source or voltage source.

Step 3) Extrude model to 3D and add cooling airflow

Step 4) Solve electromagnetic 3D problem and use losses in CFD problem to get idea about temperature and gradients.

This is a big tasks but I have about 1 year to do it. Is it worth the effort to try and do it with OpenFoam or am I better of doing it with Comsol or Ansys?

Piso / B-Piso and linearisation

noramat — Fri, 03 Sep 2010 17:42:37 GMT

Hello all. Currently i work with mhdFoam and combined it with an boussinesq-approximation like in boussinesqPisoFoam. My question is: how the piso-algorithm works in the first step in detail (the momentum predictor step). I thought in that step you take the old values of temperature, pressure and velocity to predict the new velocity and correct the values in the next steps. But how to handle the magnetic value B!? I think it's also an unknown value, which also has to be calculated implicit, like u, right? Or do i have to use also old values of B to predict the new velocity and later update it with the induction equation and the calculated velocity u? Also i have a question to linearisation.. In some articles i already found how to linearised the nonlinear convection term (use old value of velocity). I have to do the same with the terms in fvc::div(phiB, 2.0*DBU*B) and in fvc::grad(DBU*magSqr(B)) , but not in the energy-equation in fvm::div(phi, T), right? I need to know it, because i try to write out the finite-volume-discretisation using in OpenFOAM. For temporal discretisation i use the implicit Euler-Scheme and try to understand several steps. Thanks a lot! noramat

Adding Hydrogen

Cristiano — Fri, 03 Sep 2010 08:20:22 GMT

Hi all,

I am beginning to use FireFoam Solver for modelling a Jet in Hot Coflow fuelled with a mixture which is made up of methane and hydrogen.
I have successfully run my first methane -air case :confused:.
I am thinking to add hydrogen since I have hot a lot of papers which includ a lot of experimental results for methane/hydrogen mixture.
What can I do to add hydrogen in the mixture (I have never written in C++ :eek:)? Which files should I set properly to do that?

I think of modelling this flame by two different combustion models (EDC and Mixture Fraction).

Thank you in advance for your time.

Cristiano