[Kratos] SynchonizeDofs

Riccardo Rossi rrossi en cimne.upc.edu
Jue Jun 13 13:02:34 CEST 2013


Dear Bui,
             the issue you raise is quite hairy, but i think i solved it
some time ago in the builder and solver.

to begin, all of the nodes in the kratos shall have the same list of dofs,
which means that some of the dofs may be uninitialized in some of the nodes
(or even wors, may be utilized in one domain but not in the next)

in any case when dofs are syncronized the "owner" simply spawns its values
to all of the others, assuming that each node has all of the dofs...


the thing works as the builder and solver (with the modifications i
committed some time ago) shall correctly handle one node having two
different lists of active dofs on two different mpi domains.
This implies that after the solution is finished the owner of the node
shall have the correct values and hence the sync should work.

to understand how this works look around line 540 of the
trilinos_residualbased_builderandsolver....

Riccardo




On Thu, Jun 13, 2013 at 12:04 PM, Hoang Giang Bui <hgbk2008 en gmail.com>wrote:

>
> Hi
>
> I want to understand more about the method Kratos use to synchronize
> dofs between different process. I have a case like this:
>
> + Process 1 contains elements with multiple dofs (DISPLACEMENT(_XYZ) &
> WATER_PRESSURE)
>
> + Process 2 contains only conditions which involve only DISPLACEMENT(_XYZ)
>
> + node k belongs to process 2
>
> When dofs are enumerated in process 1, node k on the boundary of process
> 1 & 2 is fully enumerated with DISPLACEMENT(_XYZ) and WATER_PRESSURE
> When dofs are enumerated in process 2, node k only has DISPLACEMENT(_XYZ)
>
> When dofs are synchronized, the dof on process 2 supersede process 1.
> Which means WATER_PRESSURE dof on node k is assigned with EquationId 0.
>
> In this case what should I do to enable dof enumeration correctly in
> parallel?
>
> Ciao
> Bui
>
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-- 

Dr. Riccardo Rossi, Civil Engineer

Member of Kratos Team

International Center for Numerical Methods in Engineering - CIMNE
Campus Norte, Edificio C1

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