# Modelling rotating machinery other than AMI rotating meshes

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March 4, 2014, 07:42
Modelling rotating machinery other than AMI rotating meshes
#1
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Hi Foamers,

I have case of a rotating fan at Low- speed ie about 300-400 rpm. I have successfully carried out RAS simulations using cyclicAMI approach where, the motion of the fan is modeled as rigid body rotation of a cylindrical AMI mesh section, which has same speed as our fan. I have tried various levels of mesh refinement and differing y+ and so forth.

The screen shot is attached.

I would like to know if there are any other methods of modelling this problem, as I am not able to predict some important parameters accurately. For the attached mesh I used solidBodyMotionFvMesh for rotating inner domain/cyclicAMI. I am looking into
dynamicFvRefineFvMesh and dynamicMotionSolverFvMesh for rotating the fan.

Attached Images
 sidemesh.jpg (102.7 KB, 33 views) mesh.jpg (91.4 KB, 33 views) rotating.jpg (50.6 KB, 34 views)

 March 5, 2014, 10:55 #2 Member   Julian Langowski Join Date: May 2011 Location: Bremen, Germany Posts: 91 Rep Power: 7 Dear Fedvasu, have a look at the MRF approach using the fvOptions in the system folder. Basically you use a static mesh and add additional source terms (Coriolis acceleration) to the Navier Stokes equation. I think a tutorial can be found in incompressibel/simple somewhere. Best regards Julian __________________ πάντα ῥεῖ - Heraclitus

March 6, 2014, 04:18
error in solver
#3
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Quote:
 Originally Posted by Ruli Dear Fedvasu, have a look at the MRF approach using the fvOptions in the system folder. Basically you use a static mesh and add additional source terms (Coriolis acceleration) to the Navier Stokes equation. I think a tutorial can be found in incompressibel/simple somewhere. Best regards Julian
Hi Ruli,

I have set-up the case with fvOptions I am giving my top and bottom cylinder caps freeStream Boundary condition but I am getting following error, previously I was giving all wall boundary condition but still same error, In my case there is no inflow or outflow, all the flow is due to rotation of fan. I could share my 0.org if required.

Continuity error cannot be removed by adjusting the outflow.
Please check the velocity boundary conditions and/or run potentialFoam to initialise the outflow.
Total flux : 0.455568
Specified mass inflow : 0.493281
Specified mass outflow : 0.493281

 March 6, 2014, 06:34 making both top and bottom caps empty #4 Member   Join Date: Oct 2013 Posts: 40 Rep Power: 5 I got this error for empty boundary condition Code: ```--> FOAM FATAL ERROR: Continuity error cannot be removed by adjusting the outflow. Please check the velocity boundary conditions and/or run potentialFoam to initialise the outflow. Total flux : 0.0686486 Specified mass inflow : 0.518823 Specified mass outflow : 0.518823 Adjustable mass outflow : 0``` both inflow and outflow is same, i don't know what the problem is now!!

 March 6, 2014, 12:13 Solved by initializing with potentialFoam #5 Member   Join Date: Oct 2013 Posts: 40 Rep Power: 5 I studied motorBike case (\$FOAM/mesh/snappyHex/motorBike), I too initialized values with potentialFoam and I am running the simulation now. I would like to know are there any other methods which involve moving geometry instead MRF, to model this kind of problem I was thinking dynamicMotionSolverFvMesh of dynamicMeshDict, has anyone any experience in modeling these kind of problems?? please let me know.

 March 6, 2014, 12:45 #6 Member   Julian Langowski Join Date: May 2011 Location: Bremen, Germany Posts: 91 Rep Power: 7 Try this one: tutorials/incompressible/simpleFoam/mixerVessel2D Best regards Julian __________________ πάντα ῥεῖ - Heraclitus

March 7, 2014, 02:35
#7
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Quote:
 Originally Posted by Ruli Try this one: tutorials/incompressible/simpleFoam/mixerVessel2D Best regards Julian
Yes,
The current case which I am running is set-up like mixerVessel2D.

See I have taken two approach one with mesh motion where solidBodyMotionSolverFvMesh (I have results and analyzed them) is used for dynamic part of the mesh and another is MRF approach which you have helped me to set-up.

I am asking if there is yet another approach perhaps with mesh motion but different mesh-motion solver??

 Tags dynamic mesh, openfoam

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