I am trying to use a plastic screw extruder that I have and I would like to have it fill a cavity that I machine with an inlet and outlet hole. A simple mans injection mold/casting machine
The cavity is a ‘pillow’ shape and I need to make sure that the pillow cavity is 100 % full when the plastic exits the outlet (no air pockets). Possibly at different inlet flow rates and temperature of the cavity surface if I have to.
The cavity inlet is on one pillow corner and the outlet is on the diagonally opposite corner.
I believe that I can obtain a filling flow velocity of up to 0.14 m/s at the inlet and also have a zero pressure outlet.
I am unsure about how to define my material kinematic viscosity. This is some information I know about my ‘polypropylene’ like plastic:
I am also unsure about how to define my boundary layers (turbulence model and parameters etc) for this material and whether I have enough material specs to make this work.
I assume I wanted a transient incompressible simulation so I have started one in the project but right now I am stalled.
I have not find any successful projects/tutorials concerning plastic flow through a cavity.
I may have to vent the other two pillow corners with holes smaller than the outlet and if I see plastic coming out the outlet before I see plastic come out both the corner vents, then I plug the outlet until plastic comes out both corner vents at which point the pillow should be full and it could be removed to cool, but it would be nice to try to simulate this
First thing that came into my mind is this here: Non-Newtonian Models @ SimScale. I would assume that some of the materials used can be seen as laminar thus no k-epsilon or k-omega approach is needed but that’s just my intuition and I would probably have to look for some papers to see what the state-of-the-art is, especially for such a case
Woah!! such a cool thing you are trying to simulate. I see some problem with the placement of inlet and outlet holes. From what I have learned about the casting process, I would advice you to keep the outlet on the top and reserve one hole(in the present geometry) to serve as the inlet. In the present configuration the plastic would try to move out from the outlet face even before filling this cavity to its top.
Also, the perpendicular configuration of the inlet and outlet faces will make it easy for you to run a multiphase simulation where your liquid plastic is filling the cavity and air is moving out of the cavity from the top. But, the problem is that there are not enough materials to choose in multiphase simulations. So, only @jousefm sir can explain on how to add new materials for multiphase simulations.
Also, there are many research papers available which are using VOF approach for such problems and I am attaching some of them here- oops we cannot upload doc file .
Intuitively with a plastic state that is still very viscous, I would not expect that there is any need to worry about a Top or Bottom relationship. I do not think gravity plays much of a role here. And I was thinking that even multiphase aspect would be less important. I was thinking if I did not use multiphase we would just do transient sim and watch the cavity fill but there is likely not any basis to my intuition here.
I will look at your links tomorrow, thanks.
Also, if this gets too hard I am pretty sure that my sequential hole plugging concept (3 corner outs, plug first to see material, then plug second, then end fill when 3rd starts oozing) will work and I will just forget this sim project I just thought it would be cool to try. For the use of the pillow, it would be best not to have any runners which would have to be trimmed manually at the outlet location you suggest.
At best I would expect that maybe a sim might show me the order in which I would have to plug those corner outlets
I see it as manufacturing problem, simulation was intended to comfort your choice… I would avoid extrusion in such a tiny object production. I guess you need Face1 and Face66, Probably a pressing method would be the easiest one. In that case you would need Face1 and Face66 as outlets.
@DaleKramer there is a lot to take in here, but my first thought is that this will definitely be a multiphase flow and possibly non-Newtonian. The multiphase part I have done previously in OpenFOAM, but I wouldn’t say I am super adept at it. I have absolutely no intuition about the non-Newtonian part though; never done anything with it in my life.
I just realized that the checkbox comes when you post something in the project support section(or any public group). It will not come in private groups.
From what I understand, they should be there for ALL topics that YOU create.
Do you have them there for topics you create in all Categories in this forum?
I have never seen them on any of my topics before today (and only today on this Project Support category), since I have been told they should be there for all topics I create.
No sir, In the below img, there are limited number of materials to pick from in the multiphase simulation case. Can we somehow add/define a new material(for instance, can I add blood as my material)
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I just thought it would be cool 
to try. For the use of the pillow, it would be best not to have any runners which would have to be trimmed manually at the outlet location you suggest.
