MueLu: BlockedCoordinatesTransferFactory for interface coupled problems

[maxfirmbach]

Question

Hello everyone,

I'm trying to use the BlockedCoordinatesTransferFactory for an interface coupled problem, but fail to get it working properly.
As I understand it, for volume coupled problems, where each node carries the same amount of DOFs I just store the coordinate vector and can make usage of transfer factories to project them to a coarser level.

But what in the case of interface problems or mixed-dimensional problems?
There I would have different coordinate vectors for different domains, can the BlockedCoordinatesTransferFactory still handle these cases?

Especially for interface problems the coordinate information is beneficial for rebalancing the coarser levels at some point and also for structured grids.

Best regards,
Max

@muelu and @mayrmt

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[jhux2]

@maxfirmbach I hope you don't mind that I've migrated your question to the Trilinos Discussions section.

[jhux2]

@csiefer2 @pohm01 Any suggestions for Max?

[jhux2]

@trilinos/muelu

[GrahamBenHarper]

@maxfirmbach my understanding is that more complex scenarios like the one you described are typically handled by using Teko and MueLu together for block preconditioning, but I have not done a lot of block preconditioning with MueLu. I think @pohm01 has done some of this type of block preconditioning, including work related to the block preconditioning that Tobias did.

[maxfirmbach]

To be honest, I think I will need something similar to how the Nullspaces are handled. So each block handles an own set of coordinates and the BlockFactory handles the transfer 🤔.

[pohm01]

@maxfirmbach Unfortunately the BlockedCoordinatesTransferFactory currently only works for a single set of coordinates, as one has in the volume coupled case with a uniform number of dofs/node. If I remember correctly, the MueLu hierarchy is currently set up to only have the single Coordinates, so I think you are correct in thinking that something similar to the Nullspaces will be needed (so something like Coordinates1 and Coordinates2), and then the BlockFactory handles the transfer through the standard coord transfer instead of BlockedCoordinatesTransferFactory.