MooseApp

Specifying Application to Use

It can be useful, when running a large "combined" application like blue_crab, to specify a specific application type to run an input file with. For instance one may want to run griffin as the main application and pronghorn as a sub-application. Just as the application type for the sub-application is specified in the main input file using app_type = PronghornApp the application type for running the main input file can be specified on the command line via <blue_crab_root_dir>/blue_crab-* -i foo.i --app GriffinApp. This allows any special actions and setup specific to the application to be used.

Nonzero reallocation behavior

The MOOSE framework and libMesh work together to supply a sparsity pattern to PETSc which informs how much memory is allocated for the system matrix. If the sparsity pattern is too small, then PETSc will be forced to allocate new memory during matrix assembly if user code tries to add/set a matrix entry that wasn't preallocated by the sparsity pattern. This allocation at matrix assembly time can significantly slow down a simulation. MOOSE and libMesh are known to generate accurate sparsity patterns in most cases; however, for complex multi-body problems like mechanical and thermal contact, the sparsity pattern may be incorrect. Because of this, by default MOOSE does not error if PETSc is forced to do new nonzero allocations during matrix assembly. However, if an application developer expects their physics to have accurate sparsity patterns, they may override the default MOOSE behavior and error on new nonzero allocations. This can give the application developer peace-of-mind that their applications will not produce quiet nonzero allocations at run-time.

Overriding the default nonzero allocation behavior can be accomplished by overriding the virtual function bool MooseApp::errorOnJacobianNonzeroReallocation() const. The MooseApp default is false, although this will hopefully be changed in the not-too-distant future. Note that the application level code setting can always be overridden at the input-file level by specifying a value for Problem/error_on_jacobian_nonzero_reallocation.