Learning Forum

[mcgrat25]

I am trying to simulate the sealing of a leak in a pipe using a deformable particle, created/approximated using MPM. The below screenshots shows the particles in the vicinity of the 'leak', which is an extruded section of geometry at the top. Currently, the whole fluid domain is a singular piece of geometry. However, I want to assign particle deposition only to the wall around the leak, so that the particle will deposit itself in the position which can be seen below (currently, it bobs around the leak section when it comes into contact with it, never reaching a rest state). I wouldn't want it to deposit around the rest of the simulation wall, simply the 'leak'. The reason for this is that the real world particle will deform into the leak due to the pressure built up behind it (this can't be simulated by mpm as it assumes particles to rigid bodies, hence why I will approximate those using 'deposition'), a pressure which would occur when contacting the edge of the leak wall, but not the other general pipe walls. The only way I can think to enable this is for the 'leak' and 'pipe' to be made into separate bodies within the same 'part', allowing them to be selected as different zones in the MPM deposition user interface.

The issue with this however is that from the ansys help guide, it mentions that 'The MPM is not compatible with mesh interfaces'. I've come across 'mesh interfaces' as a boundary condition within fluent, but can't seem to find anywhere that states whether it's 100% necessary to apply this BC to regions where 2 bodies meet in a part. My question is therefore two-fold - would an 'interface' BC have to be applied to where these two bodies intersect, and if so, does that make it impossible to use MPM in cases where more than one body exists?

At the moment, on a separate test simulation, I've set up to see if MPM is possible with 2 bodies - my particle keeps disappearing as it comes into contact with the region where the two bodies meet, however, I'm not sure if this is because you cannot use MPM for geometries with multiple bodies, or because I've set up the model wrong in some other way.

It does strike me as odd that you wouldn't be able to use different bodies within MPM - photos from Ansys promotional material for MPM apply it in models containing 'filter' elements which appear to be constructed from different bodies (see bottom images).

If there is a way around this, please could you let me know? Thanks in advance.

[Rob]

You can define a surface label so that (for example) a single cube has 6 separate surface IDs. n

[mcgrat25]

nHow is this done? Is it within design modeller, meshing, set-up etc?n

[Rob]

DM or Meshing, use a Named Selection and select the face you want to label. So, in your case the small pipe may need a label wall_side_trap to make it clear when you're setting up the solver. The main pipe wall can have a different name, or no name as it'll automatically be a wall in Fluent. n

[Amine Ben Hadj Ali]

The promotion material is but old but still actual. Try to have a multi-body part to have a conformal mesh. It can be possible to get rid of the limitation by disabling internal checks if and if the particles are not crossing any interfaces.n