[ameen@cfd]

Hello everyone,

I am working on centrifugal pump. I have generated the mesh in GridPro and converted it into openfoam. I have generated three fluid regions (say fluid1,fluid2 & fluid3) within the domain. The fluid1 (rotating) is the region surrounding the rotor and fluid2&fluid3 (non rotating) are near the outer boundary (outer casing). These regions are written in cellzone files generated after conversion.

My query is,
1. Will it be sufficient to define fluid1 (rotating) in fvoptions file or do i need to define the other regions as well. If yes then how can i do it.

2. If i donot define the non rotating cellzone will the solver consider it while solving. figure4_fluidregion_1.jpg

figure5_fluidregion_2.jpg

figure6_fluidregion_3.jpg

Thank you.

[fumiya]

Hi,

Only rotating region has to be defined in fvOptions file.
You might want to take a look at incompressible/simpleFoam/mixerVessel2D tutorial.

Hope this helps,
Fumiya

[ameen@cfd]

Thank you Fumiya Nozaki, that was quite helpful. But that arises few more doubts.

1. Isn't it necessary to define relative velocity for the rotating parts. But as I can see in the tutorial there is no relative velocity defined. How does this work.

2. The other thing is I tried to solve my problem as per tutorial, but when I tried standard K-epsilon model my solution was giving me this error.

Time = 1.4

smoothSolver: Solving for Ux, Initial residual = 1.47848e-23, Final residual = 1.47848e-23, No Iterations 0
smoothSolver: Solving for Uy, Initial residual = 1.78189e-22, Final residual = 1.78189e-22, No Iterations 0
smoothSolver: Solving for Uz, Initial residual = 1.33499e-21, Final residual = 1.33499e-21, No Iterations 0
GAMG: Solving for p, Initial residual = 5.54095e-09, Final residual = 5.54095e-09, No Iterations 0
time step continuity errors : sum local = 1.3739e+119, global = -7.70269e+101, cumulative = -7.70269e+101
#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#2 in "/lib/x86_64-linux-gnu/libc.so.6"
#3 Foam::multiply(Foam::Field<double>&, Foam::UList<double> const&, Foam::UList<double> const&) in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#4 void Foam::multiply<Foam::fvPatchField, Foam::volMesh>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libincompressibleTurbulenceModel.so"
#5 Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > Foam:perator*<Foam::fvPatchField, Foam::volMesh>(Foam::tmp<Foam::GeometricField<doub le, Foam::fvPatchField, Foam::volMesh> > const&, Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > const&) in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libincompressibleRASModels.so"
#6 Foam::incompressible::RASModels::kEpsilon::correct () in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libincompressibleRASModels.so"
#7
in "/opt/openfoam230/platforms/linux64GccDPOpt/bin/simpleFoam"
#8 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#9
in "/opt/openfoam230/platforms/linux64GccDPOpt/bin/simpleFoam"
Floating point exception (core dumped)

But again when I used realizableKE this error didnt occur and is running. Is there any specific reason for it.

Thank you.

[fumiya]

Hi,

1. I think this document might clear up your doubts (page 17):
http://www.tfd.chalmers.se/~hani/kur...inery-OFW7.pdf

2. The kEpsilon model is used in this tutorial:
https://github.com/OpenFOAM/OpenFOAM.../RASProperties

Hope this helps,
fumiya

[ameen@cfd]

Thank you for the information. I have implemented it to my problem and running quite well.

If there are any issues i'll post them again.

[ameen@cfd]

Hello Fumiya, Thanks for your help I am able to run my problem. Though it seems, it would take lot of time to converge.

Mean time I was thinking if particle tracking with MRFSimpleFoam is possible or not. The fluid I considered is blood, so in order to calculate blood damage due to stresses I want to implement particle tracking. Can you suggest how can I actually implement it.

Thank you.

[ameen@cfd]

I have been running my simulations for over 10000 iterations but I am not able to achieve convergence even below 10^-4. Can anyone help me to sort out this issue.

Details.

I'm solving centrifugal pump containing 5.4 Million Hexa cells using MRFSimpleFoam.

I have attached my boundary condition files and fvschemes and fvsolutions files.

Kindly provide some feedback.
U_P_K_E_file.pdf

fvSchemes.pdf

fvSolutions.pdf
Thank you.

[ameen@cfd]

Can anyone please help me regarding the convergence.

I have changed from kepsilon to kOmegaSST and tried even changing the under relaxation factors. I changed the scheme to upwind. Even then I am not able to reach convergence upto 10^-4.

Any suggestions. The geometry and P, U conditions is same as defined in above

postresidualplot.jpg.