How to make venting? Is it possible?

Klemen · September 5, 2017, 18:19

Hello Foamers!

I have a modified interFoam solver with which am trying to simulate injection molding. Cavity does not have any outlet and inside of it is initially air.

While filling this cavity with fluid(polymer), air should go out but not polymer.

What should I do?

How to make the polymer fill the cavity and vent the air out without specifying an outlet?

In reality, air leaves the cavity on many places, but it's flow is not important.

For any answer I will be very thankful!

Kind Regards,

Klemen

elvis · September 17, 2017, 11:59

https://www.cfd-online.com/Forums/op...-openfoam.html

Boundary conditions when simulating injection molding

Polymer processing injection molding application

krikre · October 1, 2017, 11:39

The boundary condition outletPhaseMeanVelocityFvPatchVectorField is almost the solution to this problem. It's derived from the mixed boundary condition, so it switches between the zero gradient and zero value based on the alpha field.

This needs to be done for both the velocity and pressure fields. I made the modifications and it seemed to work for a while but then divergence occurred which I didn't have the time and knowledge to resolve. I might post an update if I get it to work properly in which case I'll provide an example case. Until then the code will be on a temporary branch 'bcLibTemporary' in my repo.

samiam1000 · September 4, 2020, 03:21

Hi Klemen,

I am working on a similar problem. Do you have any update, by chance?

Thanks a lot,
Samuele

JuRe09 · June 21, 2022, 15:24

Hey Samuele,

did you solved the challenge with the venting BC? Could realy need some guidance on this topic...

September 5, 2017, 18:19	How to make venting? Is it possible?	#1
Klemen New Member KlemenFr. Join Date: Jul 2017 Location: Slovenia Posts: 1 Rep Power: 0	Hello Foamers! I have a modified interFoam solver with which am trying to simulate injection molding. Cavity does not have any outlet and inside of it is initially air. While filling this cavity with fluid(polymer), air should go out but not polymer. What should I do? How to make the polymer fill the cavity and vent the air out without specifying an outlet? In reality, air leaves the cavity on many places, but it's flow is not important. For any answer I will be very thankful! Kind Regards, Klemen

September 17, 2017, 11:59		#2
elvis Senior Member Elvis Join Date: Mar 2009 Location: Sindelfingen, Germany Posts: 620 Blog Entries: 6 Rep Power: 24	https://www.cfd-online.com/Forums/op...-openfoam.html Boundary conditions when simulating injection molding Polymer processing injection molding application Klemen likes this.

October 1, 2017, 11:39		#3
krikre Member Kristjan Join Date: Apr 2017 Location: Slovenia Posts: 36 Rep Power: 9	The boundary condition outletPhaseMeanVelocityFvPatchVectorField is almost the solution to this problem. It's derived from the mixed boundary condition, so it switches between the zero gradient and zero value based on the alpha field. This needs to be done for both the velocity and pressure fields. I made the modifications and it seemed to work for a while but then divergence occurred which I didn't have the time and knowledge to resolve. I might post an update if I get it to work properly in which case I'll provide an example case. Until then the code will be on a temporary branch 'bcLibTemporary' in my repo. Klemen and JuRe09 like this.

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September 4, 2020, 03:21		#4
samiam1000 Senior Member Samuele Z Join Date: Oct 2009 Location: Mozzate - Co - Italy Posts: 520 Rep Power: 19	Hi Klemen, I am working on a similar problem. Do you have any update, by chance? Thanks a lot, Samuele

June 21, 2022, 15:24		#5
JuRe09 New Member Julian Re Join Date: Jan 2022 Location: Germany Posts: 11 Rep Power: 4	Hey Samuele, did you solved the challenge with the venting BC? Could realy need some guidance on this topic...