Dear Paola,

Thanks for the files. In case you prefer my e-mail is mnobrega@dep.uminho.pt.

Regarding the simulation we need adequate rheological models for both raw materials. As a starting point, there is the chance of using typical data published in the literature. However it will be an approximation.

If those materials weren't already characterized, I can do it in our labs. For that I'll need small samples of each one, circa 5 kg would be enough.

Can you send the identification of both material grades? Then I’ll check if I can get those samples from our labs or from a Portuguese supplier.

Best regards,

Miguel

Hello all!

Paola: some questions from my side:

What is the draw down velocity (block velocity) at the exit of the die?
The geometry is provided in inches, correct? Can you confirm that after conversion to meters the total length of the flow channel in z-direction is 0.377 meters?
At which temperature are you operating the extrusion die?

Regarding IGES as CAD format:
Pros: nearly every mesher can handle it
Cons: repairs might be necessary
Indeed, most time for the manual work must be spend on repairing bad geometries when dealing with complex extrusion die designs. If you can stay with the same CAD kernel for design and meshing you will save a lot of time.

I had no problems converting your iges files to .sat format, which is (beside of .x_t) my preferred format for meshing. Unfortunately this easy conversion is not always possible.

I generated meshes for your extrusion die that can be run with OpenFOAM®®. If you or Miguel can provide the appropriate rheological models and material data I can set up the final cases for OpenFOAM®®. I attached some adhoc results for the same material as I used in the capillary case.

My typical workflow to handle your kind of extrusion die is:
- import the iges file into a mesher
- generate a rather coarse tetrahedral mesh
- run a quick simulation with OpenFOAM®® to check the overall design
- if design is not totally awful: generate a fine tetrahedral mesh with boundary layers
- run a simulation with OpenFOAM®® again and make a detailed analysis of the die design

Since you (Paola and Carlos) may want to use the simulations at an industrial scale, and therefor need one or more simulations every day: you will have to go for a commercial mesher. The free meshers available do need too much manual work to do the meshing. With a good commercial mesher you can reduce the manual working time for meshing to less than an hour. Then a couple of minutes to set up the OpenFOAM®® case. Depending on your hardware a few hours of machine time for the simulations. Then depending on the results a couple of minutes up to an hour of manual time to do the post processing.
On the other hand, if someone wants to make detailed scientific analysis of the die design, it is necessary to spent much more time into the meshing. Ideally a fine hexahedral mesh for most parts of the flow channel would be the result.

I can give more comments and ideas regarding the die design after the simulations with the correct material properties.

Regards

Martin

Miguel/ Martin;

I'm sending you to your personal emails the specification sheet for both polymers, hope this information be enough.

In regards your questions Martin;
-The draw down velocity is 75 ft/min
-The geometry is in inches
-The total leght of the main cavity is 0.14859 mts
- temperature is 190 C
- We design the solid in autocad 2012 and then with inventor we save it in iges format. We believe that do it like that it will be fine

Could you tell us the mesher that you are usign? We installed netgen but we couldnt been able to tranfer the neutral file to openfoam format. Could you give us some help with the mesher or the appropiated way to do this in openfoam

Regards and thank you for all.