Polyflow coextrusion – predicting swell and interface layer between polymer


    • Rayanne Pinto Costa


      I am trying to simulate a 3D isothermal die coextrusion that the die has a complex geometry. The two polymers are kind of concentric. So the internal polymer does not touch any wall inside the die. My goal is to obtain the distribution/interface layer between the two polymers inside the die and outside, and also the obtain the extrudate swell. I have tried many setups already. I just want to make sure I am using the right setup and practices. Here are my questions:

      1.On my simulation, I am using the species methods for obtaining interface of the materials and a free surface for the extrudate outside. I tried using interface boundary condition before but that did not work. The velocity at the end of the extrudate (jet outlet) is uniform (flat) but the pressure is not all the same in the outlet (the boundary is fn=fs=0). I was wondering if that means I need to make the jet longer?

      2. I have been using the species methods to predict the interface between the two fluid inside the die and in the jet .However, I tried using the adaptative mesh to try to get more accurate results. The options for the adaptative mesh is not available. I think the the issue may be related to the mesh. I used tetrahedral for the die shape and  bricks for the free jet. My questions is what are the requirements or tips/tricks in the mesh to be possible use the adaptive mesh. Also, Is it possible to use two different meshes? One for the die with complex geometry and another for the jet which is sliceable?

      3. How is the adaptive mesh different from the species methods and the interface when using 3D geometries with two polymers?

      4. About the jet, is it recommended to also use mesh inflation on the jet surface or is that recommended just for the wall of the die?

      5. About the Ansys Polyflow capabilities, does Ansys have an optimization option that enable to automatically calculate the exit deviation of Velocity and Temperature? Like, similar to what PolyXtrue from Polyflow does.

      I appreciate the help. Thanks.


    • Nilay Pedram


      You can refer to the example cases in Polyflow help page: Ansys Product Help

      There are a few examples which uses adaptive meshing, optimization, etc. Those cases might be helpful for your setup and might answer your questions.

      If you are not able to access the link, refer to this forum discussion: How to access the ANSYS Online Help


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