Learning Forum

[Patrickodon]

In 3D modelling, when I go to Cell Zone Conditions and select my material:

 

 

I change the Phase to calcium-phase:

 

 

then I hit Apply, but for some reason when I close and re-open the Cell Zone Conditions, the Phase is back to mixture. Why is this not changing permanently?

 

Here is my calcium Phase:

 

Even selecting Fixed Values and changing Phase to calcium-phase keeps it at mixture when you Apply and close/re-open:

 

Edit: further playing with Ansys tells me that you can change the Phase here:

 

 

How do I change my calciumbody Zone to calcium, and hydrogelbody Zone to hydrogel? When I chang in the Phase in the picture, it changes for everything 

[SRP]

Hi,

When modeling multiphase flow, you will not specify the materials here.

For more details, please refer to user's guide: 7.2. Cell Zone Conditions (ansys.com)

If you are not able to access the link, please refer to this forum discussion: Using Help with links (ansys.com)

Thank you

Saurabh

[Patrickodon]

I've changed the Model to Eulerian and I'm trying the settings in this tutorial: _ANSYS Customer Portal_Training Materials_eulerian_multiphase_granular

[Rob]

Are the zone separated by walls? Ie do you have several separate zones which cannot mix?  

[Patrickodon]

Yeah I've a fair few walls:

 

 

Which I've been trying to deal with since here /forum/forums/reply/246771/ :

 

 

I don't have a "mesh interface" Type in the Type menu - how do I get one? My current Mesh Interfection section is:

 

 

 

[Rob]

The nonconformal set up was change a couple of versions back. For planar connections that's good, for curves it's occasionally not so good. The best approach is usually to use share topology to create a conformal mesh, it's computationally more efficient and avoids jumps in cell size if you're not careful. 

[Patrickodon]

Is "share topology" along the lines of allowing "merge topology" in DesignModeler? I've never used/don't know what a "conformal mesh" is. Is it possible for me to set a body as calcium, and a body as hydrogel, in my current state, and turn the wall between the calcium and hydrogel into a plane that allows mixing between them?

[Rob]

OK, share topo connects the volumes, so rather than having two faces at a volume contact you have one. That gives you a linked mesh, with nodes/faces shared between the volumes. That'll be covered in some of the courses under Learning. 

Multiphase is a fun area to get into. We assume that all phases flow, so solids are granular and behave as fluids with some extra models to account for particle contacts.  In your case, with phases mixing the whole domain should be mixture. You then patch zones to be a single phase (sort of - read the model theory) to give the starting point.  If the hydrogel disolves the calcium you have a different problem set up which may or may not need a completely different approach. 

[Patrickodon]

So is my current method not possible? Defining the bodies as calcium/hydrogel is not allowed/solvable?

 

I can look into Multiphase/patching if so.

[Rob]

It's possible, but not how the multiphase models work. As you've not explained what you're doing, or posted any images it's difficult to work out what you actually need to set up. 

[Patrickodon]

 

OK;

 

Here is my 3D cylinder body:

 

 

I’m doing 3D mixing in a stirring tank, with a main zone of water (A) and a small cubic section of calcium (B) being mixed (picture is a cross-section of the model). The grey section is a "mixing zone" which rotates about the "blank" zone which signifies the stirrer bar. This simulates the rotation of a stirrer bar in the liquid.

 

 

In DesignModeler, I drew the water cylinder, then drew the calcium cuboid inside that cylinder and used the Boolean command to Subtract the calcium from the water (while retaining the calcium section)

 

Some Interfaces have autocreated (hydrogel is just water):

 

 

 

 

[Rob]

OK. Assuming the calcium is a "fluid" rather than a disolving solid make a multibody part (DesignModeler) or use ShareTopology (SpaceClaim) to get a conformal mesh. Label the volumes to suit. Then in Fluent you patch in the materials. Note, a granular phase has a packing limit, so always patch those at 0.01 below the limit to avoid interesting consequences. 

If the calcium is disolving you have a different problem, and you may need to read up on moving mesh, surface reactions and UDFs. 

[Patrickodon]

Yesterday, I played around with what I had a bit more - that is, I restarted it, re-set it up with the same settings, modified a few based on (_ANSYS Customer Portal_Training Materials_eulerian_multiphase_granular) and, amazingly, finally got mixing occuring.

 

"OK. Assuming the calcium is a "fluid" rather than a disolving solid make a multibody part (DesignModeler) or use ShareTopology (SpaceClaim) to get a conformal mesh. Label the volumes to suit. Then in Fluent you patch in the materials."

 

Bold is what I had. I patched the calcium into the calcium cuboid at 0.5 Volume Fraction.

It took me 40-60 hours to get the ropes on DesignModeler over the past few months (comfortable enough that I can make the complex shapes I'm currently working on; the complexity of the actual model relative to my DesignModeler skills was why I had to go so simple at the start); SpaceClaim would be another big time sink.

 

Thanks for your help, genuinely much appreciated.

[Rob]

You're welcome. 

Learn Discovery (geometry) rather than SpaceClaim, it's the newest of the geometry tools and expect to see further functionality added over the next releases. I use a mix of DM, SpaceClaim and Discovery depending on what I'm doing, but generally focus on the solver. 

Glad you liked the Eulerian course. :) 

[Patrickodon]

We're at Ansys 2022 R1 in college (not R2), so I imagine we don't have access - our only available ones in Geometry are DesignModeler and SpaceClaim. I'm very proficient in DesignModeler now, with the time I've put into it haha.

I've done that tutorial about ten times over, with the original geometry and my own. I'm genuinely becoming an Ansys expert from scratch with the amount I'm doing at it, I'm just terrible at picking at simple things if I haven't done them before so I have to scour the forums/YouTube/Google for whatever I can find!