libROM / MFEM v4.6 updates + Advection-diffusion

[dreamer2368]

libROM PR #274 update

• dataset name change for libROM snapshot matrix files: dataset suffix _000000 is removed.
• Enforced the use of CAROM::Dataset::formats

MFEM v 4.6 update

MUMPSSolver changes

• MUMPSSolver initialization requires MPI_Comm
• MUMPSSolver::MatType is changed.
  • Now StokesSolver should use MUMPSSolver::MatType::SYMMETRIC_INDEFINITE.
  • StokesSolver::SetupMUMPSSolver takes input argument bool set_oper and uses MUMPSSolver::SetOperator only if set_oper is true. For SteadyNSSolver, set_oper is set false.

SubMesh changes

• SubMesh does not use SubMesh::GENERATED_ATTRIBUTE any more for the generated boundaries of submeshes, instead parent.bdr_attributes.Max() + 1.
• Reflecting this, boundary attributes for interfaces are set from parent.bdr_attributes.Max() + 2, both for SubMeshTopologyHandler and ComponentTopologyHandler.
• Minor fix in ComponentTopologyHandler::SetupReferencePorts: the input mesh/component-wise/ports/.../file for port file name is optional.

Advection-diffusion equation

• AdvDiffSolver solves the advection-diffusion equation given a Peclet number.
• The velocity field must be provided either in analytic form or with a solution from StokesSolver or SteadyNSSolver.
• Currently StokesSolver or SteadyNSSolver only provides FOM velocity field.
  • This limits ROM for AdvDiffSolver to be always built from a global system. Fully component-wise ROM for AdvDiffSolver requires taking velocity POD basis from StokesSolver or SteadyNSSolver.