Simulate cyclone separators by MPPICFoam: large errors when scaled down to mm
 

Dear All,

I want to simulate cyclone separators by MPPICFoam. For that, I draw a cyclone configuration in Catia and then by applying snappyHexMesh, the grids(meshes) were produced. When I used transformPoints to change the dimension of this configuration into millimetre and then applying MPPICFoam. But after some seconds I have this message:


PIMPLE: iteration 1
smoothSolver: Solving for U.airx, Initial residual = 0.770981, Final residual = 6.20484e+09, No Iterations 1000
smoothSolver: Solving for U.airy, Initial residual = 0.514037, Final residual = 7.5459e+09, No Iterations 1000
smoothSolver: Solving for U.airz, Initial residual = 0.741431, Final residual = 4.11844e+08, No Iterations 1000
#0 Foam::error::printStack(Foam::Ostream&) at ??:?
#1 Foam::sigFpe::sigHandler(int) at ??:?
#2 ? in "/lib/x86_64-linux-gnu/libc.so.6"
#3 Foam::GAMGSolver::scale(Foam::Field<double>&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&, Foam::Field<double> const&, unsigned char) const at ??:?
#4 Foam::GAMGSolver::Vcycle(Foam::PtrList<Foam::lduMa trix::smoother> const&, Foam::Field<double>&, Foam::Field<double> const&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::PtrList<Foam::Field<double> >&, Foam::PtrList<Foam::Field<double> >&, unsigned char) const at ??:?
#5 Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const at ??:?
#6 Foam::fvMatrix<double>::solveSegregated(Foam::dict ionary const&) at ??:?
#7 Foam::fvMatrix<double>::solve(Foam::dictionary const&) at ??:?
#8 ? at ??:?
#9 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#10 ? at ??:?
Floating point exception (core dumped)
....

To remove this error, I checked all files to be sure about accuracy of them. Moreover, I tried to simulate that problem without any turbulence and again I faced by that message:(. Then, I considered that problem without any particles and found that the problem solution is working but as soon as particles are considered, the simulation is not working and I have above message. Till now, I could not find what the problem is and what I should do to remove this problem and run my simulation:confused:.

Could you please guide me?!!!

Quick answer/question: Not enough information. Please provide more details, as explained here: http://www.cfd-online.com/Forums/ope...-get-help.html

For example, we need to know how you configured the files respective to the particle properties and sizes.

Dear All,

I want to simulate industrial cyclone separators by MPPICFoam too. For that, I draw a cyclone configuration in SolidWork and producted a STL file, Now I should product grids (meshes) by editing blockMeshDict and then snappyHexMesh...

1- How should I change the blockMeshDict file (vertices, blocks, edges, boundary...) of OpenFoam example and then snappyHexMesh?

2- Should I change the dimensions of the industrial cyclone in OpenFoam?

please help me.

Thanks

Hey Ali, when u want to use blockMesh you should consider this fact that the planes of your cube should be fitted with the surface of the cyclone....it's too important for this simulation.
The answer of your second question depends on the dimensions you have considered when you were drawing thee configuration in Solidworks. That is, if you have considered the distances on meter and in OpenFoam you need the mm, you have to change the dimension in OF but it's not needed if you have not.

Hi Dosin, thanks for your comment.
1. That's mean should I consider the configuration as 2D surface?
2. But My mean in question no.2 was about the required dimensions of cyclone in OpenFoam for the maximum number of cells? Because on industrial scale, the cells number are many more.

Hey Ali,

1. No, u can't use 2D in OpenFOAm. I meant you have to consider the points of your cube so that they're fitted with the outer surface of your cyclone configuration. For instance if the max X(or Y or Z) is +20, you should consider it as your max X(Y or Z) of your cube.

2. If you use the snappyHexMesh you can control the number of your cells there.... The dimensions of the configuration in CFD is independent from min. or max. numbers of the cells.. I think it's better if u use exactly the dimensions of the cyclone was used in experimental investigation...

MPPICFoam error!!
 

Dear All,
I run cyclone example in tutorials of the OpenFOAM version 4, but it has ERROR!!!
Why???

Please help me. I really need your help.
Thanks in advance.

the parameters of folder 0 in cyclone example for twophase flow (water+air)
 

Dear Dosin,
I need to know the parameters of folder 0 in cyclone example for twophase flow (water+air)? Please help me.

Thanks a lot,
Ali

hello ebtedaei,
I think you need to give more information,what version of OF what tutorial

As far as I know OF works with m not mm so if you scaled down to mm your model will be very big and your meshsize as well. This will give a problem.

I do not know enough of this solver to help with the details, but I hope this helps
Wouter