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- - **Viscoelastic flow modeling in rotorstator system**
(*http://www.cfd-online.com/Forums/openfoam-solving/58746-viscoelastic-flow-modeling-rotorstator-system.html*)

Dear CFD experts,
I would lDear CFD experts,
I would like to know the capability of OpenFOAM to model viscoelastic flow in Rotor-Stator system. I already read that there are few work on viscoelastic flow modeling in stationary system, but how about the Rotor-stator system? I am planning to model the flow in twin screw extruder to elucidate the shear stresses and looking for the rightest solver to start with. Is OpenFOAM one of the choices in this case? I would be glad if you could give me the situation of its capabilities and the necessities to implement the viscoelastic flow modeling in rotor-stator systems? My be some more details would be helpful. The Simulation will be 3D and the interaction between rotor and stator is quite high and important. We will not simulate the whole extruder but just one pair of co-rotating kneading elements. The goal is application of different viscoelastic models to determine the one that describes the flow better. And lastly, it wont be an industrial project but PhD. Thanks and best wishes Ankur |

Hi Ankur!
I think for the wHi Ankur!
I think for the whole solution you'll have to construct your own solver. There used to be a version of the mixer2D-tutorial with mesh motion (in version 1.3, for icoDyMFoam) and old versions of interFoam used to support mesh-motion (not totally sure) I think both (mixer2D-tutorial) and interFoam with movement-support can be found in Hrv's dev version Bernhard |

Hi Ankur,
I would suggest:
Hi Ankur,
I would suggest: 1. Search for the solver, which is suitable to solve the problem generally for a newtonian liquid. (turbulent, laminar? free surface?...) 2. look an all physical equations in detail what changes are necessary if you introduce a general stress tensor, instead of newtonian stress tensor And then of course implementation of an additional PDE system is necessary to solve for your viscoelastic model. For icoFoam I added a 4-mode Phan-Thien/Tanner viscoelastic model in the past...so far completely untested... and "quick and dirty hack" linked here: http://www.cfd-online.com/OpenFOAM_D...es/1/6356.html From my experience with other (commercial) CFD codes and knowledge from viscoelastic models I would conclude, that for this complex problem programming of a suitable solver in OpenFOAM is the only reasonable choice. Can you tell, from which university you are? Greetings |

Hi Ankur,
you are correct Hi Ankur,
you are correct FEM is the dominant CFD method for twin screw simulation. But MOURS, M.; REICHELT, D.; WAGNER, H.G.; GILBERT, N.; HOFMANN, J.: Melt conveying in co-rotating twin screw extruders: experiment and numerical simulation In: International Polymer Processing (2000) is an example where FVM has successfully employed using COMET which later became cd-adapco STAR CCM or STAR-CCM+ POKRIEFKE, G.: CFD-Analysis of free surface flow inside a twin screw extruder, 22nd CAD_FEM User's Meeting, International Congress On FEM Technology with ANSYS CFX & ICEM CFD Conference, Dresden, 2004 is an other example for FVM BEM using BEMflow has been tested simulating twinscrews but uses only newtonian fluids, => not suitable for your needs. Polyflow uses mesh superposition technique to simulate twin screw extruder, but don't look to critical at the results "INSIDE" the screws ;-) Yes, I said inside and mean inside. just my 2cents wish you all the best Elvis |

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