Re: [Libmesh-users] mesh coarsening

[Michael P. <pov...@in...>]

>
> Basically what's going wrong here is that uniformly_coarsen() was only
> designed to be called following uniformly_refine(); if it's called on
> an arbitrary mesh it can flag level 0 elements for coarsening,
> flag elements for coarsening whose siblings can't be coarsened, etc. -
> problems that _coarsen_elements() can't handle.  It shouldn't be too
> hard to extend uniformly_coarsen() to handle arbitrary meshes, though;
> a single call to make_coarsening_compatible() before
> _coarsen_elements() may be sufficient.
> ---
> Roy
>
I followed your suggestion. Namely, I put make_coarsening_compatible()  
before _coarsen_elements().
The coarsening worked.  But  when I tried  to refine the mesh again for 
the next calculation, I have got errors:

Bad element ID = 64, Bad neighbor ID = 19
ERROR: Active Element at level 1
with ancestor parent share ancestor neighbor at level 0
[0] src/mesh/mesh.C, line 559, compiled Jun  7 2007 at 09:39:33

Program received signal SIGABRT, Aborted.
[Switching to Thread 1033350528 (LWP 1581)]
0xffffe410 in __kernel_vsyscall ()
(gdb) up
#1  0x3cf20821 in raise () from /lib/tls/i686/cmov/libc.so.6
(gdb) up
#2  0x3cf21fb9 in abort () from /lib/tls/i686/cmov/libc.so.6
(gdb) up
#3  0x3ae1f0dd in Mesh::find_neighbors (this=0x85efca8) at 
src/mesh/mesh.C:559
559                   error();
(gdb) up
#4  0x3ae29552 in MeshBase::prepare_for_use (this=0x85efca8,
    skip_renumber_nodes_and_elements=false) at src/mesh/mesh_base.C:92
92        this->find_neighbors();
(gdb) up
#5  0x3ae7353e in MeshRefinement::refine_and_coarsen_elements 
(this=0xaf8cba2c,
    maintain_level_one=true) at src/mesh/mesh_refinement.C:408
408           _mesh.prepare_for_use ();
(gdb) up
#6  0x3ca57ed7 in TunnelingCurrent::do_solve (this=0x80f4ec8) at 
TunnelingCurrent.C:283
283               mesh_refinement.refine_and_coarsen_elements();

My question: is it possible to use mesh object as I do, namely, 
adaptively refine and uniformally coarsen and do it several times?
Or I should create a copy of a mesh?

Thank you,
Michael.