Learning Forum

[anthony.broadhead]

We are trying to use Discovery AIM to view the extrudate velocities throughout the Die, and try to even those velocities up at the Die lip face, by changing the geometry in the die pre-land area. The problem I am experiencing is no matter how I change the geometry in the pre-Land area, the velocities at the die lip seem to remain unchanged.

Also Is there a PDF manual available for Discovery AIM.

[Gaurav Sharma]

Hi Tony Broadhead

Can you again share this model as well and that will help me better understand your concern.

I am sorry but I dont think the manual is available in PDF format. Though, there is some way to access help offline using ANSYS customer portal. Please let me know if you are interested in pursuing that and I can share the required details.

Thanks & Regards,

Gaurav

[anthony.broadhead]

Gaurav_ANSYS 

 Hi Gaurav,

 

            Please see the attached archived file Duva-016-03xe-125k 600Pa 0.75Mm and a similar file

             with the geometry in the pre land area quite different, but you will see that the velocities distribution

            and magnitudes at the die lips are very similar.

[Gaurav Sharma]

Tony Broadhead 

It seems you missed the attachments.

Regards,

Gaurav

[anthony.broadhead]

Hi Gaurav,

          The file would not upload. I will try again.

                      Tony.

does not look as if file has uploaded

[Gaurav Sharma]

Hi Tony Broadhead

I compared the two models you shared and have a different inference. If you look at the max and min velocities, i can see some change there which indicates the design changes between the two models does impact on the velocity profile. please have a look and confirm

 

Thanks & Regards,

Gaurav

[anthony.broadhead]

Thanks Gaurav,

       I do not know what Velocity X is. You can see from the colors that there are opposite colors on each side of center line of the extrudate geometry. For example any similar areas on left hand side of the center line that are yellow or red. On the right hand side are light blue or dark blue. Any areas on the right hand side of the center line that are yellow or red, on the left hand side are light blue or dark blue. This can not be correct for a graphical representation of the fluid flow distribution in the direction from the inlet to the outlet. Velocity magnitude is what I think we should be looking at, or Velocity Z. Please see the attached images. 

I am using the "Determine die lip shape" option, within the polymer extrusion template. Is this the correct or best option to view the velocity distribution across the extrudate profile section. Other options are "Predict Extrudate Shape" & " Analyze Flow within Die". Both the latter options allow the additional physics option to be selected " Restrictor ".  The help section on this additional option says " Select Restrictor to include a solid structure in the polymer flow region for optimum melt flow distribution. I am looking forward to your reply.

 

           Tony.

[Gaurav Sharma]

Tony Broadhead 

The option that you must use while setting up your simulation, depends on the end goal of your analysis:

• To investigate the flow of the molten polymer within just the die itself, select Analyze flow within die.
• To determine the shape of the extrudate based on the geometry of the die, material characteristics, and operating conditions, select Predict extrudate shape. 
• To determine the shape of the die lip corresponding to the desired cross section of the extrudate, select Determine die lip shape

For each of the above conditions, you can get the velocity profiles of the flow.

This is also mentioned in the Help document here. I strongly recommend to go through the Help or courses on ALH to help you begin efficiently with the Extrusion/Inverse extrusion problems.

For the current problem, the VelocityZ plots that you are interested in also shows different magnitude for the two different pre-lands, indicating the change in preland's geometry does affect the flow. Please highlight what confusion you are running into here so that I can help you better.

PS: The velocityX plots I showed are correct considering the YZ plane divides the domain into two halves. This means velocityX on one half is in positive direction and other half is in negative and hence the contour looks like what it is.

Thanks & Regards,

Gaurav

[anthony.broadhead]

Hi Gaurav,

 

          Thanks I understand the different contour colors now. Our objectives are to even out the velocities in the die land / die lip area, by changing the pre-land geometry or by introducing a restriction to the flow at a specific area, or both. This would result in evening out the contour colors on the velocity Z & velocity magnitude, viewing modes within Ansys AIM, so that the  cross section images I sent you would show, mostly blues and greens and very little reds and yellows, around the die land area. For example the red and yellow pockets shown in one of the images, at the bottom and top of the extrudate profiles. We would try to make these more blue and green by using the above mentioned methods. I have successfully introduced a restriction in the flow by using the method that you showed me Gaurav. This seems to have had a positive effect on the velocity distribution in the die land, so I think we are heading in the right direction.

 

            Tony.