Post-processings

In this section, we describe the post-processing options available in MFEM-MGIS.

Warning

This section is under construction

The ParaviewExport post-processing

This post-processing allows to export the unknowns of a nonlinear evolution problem for visualization in paraview:

• Key: ParaviewExportResults

Example:

problem.addPostProcessing("ParaviewExportResults",
                          {{"OutputFileName", "SatohTestOutput"}});

Results

It is also possible to extract only portions of the mesh by defining either the boundary zones or the materials (domain attributes). This is particularly useful for reducing the size of output files when only a small part is to be studied.

Example

std::vector<mfem_mgis::Parameter> materials{"Attr1","Attr2"};
std::vector<mfem_mgis::Parameter> bdrs{"left","right"};
/** You can not define Materials and Boundaries in a single post processing */
problem.addPostProcessing("ParaviewExportResults",
    {{"OutputFileName", "TestPPSubMeshOutputDir/AllMesh"},
    {"Materials", materials},
    {"OutputFieldName", "Displacement"},
    {"Verbosity", 1}});
problem.addPostProcessing("ParaviewExportResults",
    {{"OutputFileName", "TestPPSubMeshOutputDir/Attribute1"},
    {"OutputFieldName", "Displacement"},
    {"Material", "Attr1"},
    {"Verbosity", 1}});
problem.addPostProcessing("ParaviewExportResults",
    {{"OutputFileName", "TestPPSubMeshOutputDir/Attribute2"},
    {"OutputFieldName", "Displacement"},
    {"Material", "Attr2"},
    {"Verbosity", 1}});
problem.addPostProcessing("ParaviewExportResults",
    {{"OutputFileName", "TestPPSubMeshOutputDir/Boundaries"},
    {"OutputFieldName", "Displacement"},
    {"Boundaries", bdrs},
    {"Verbosity", 1}});

Note

Boundary and Material names are defined by the problem using the key words: “Boundaries” or “Materials” such as:

• {“Materials”, mfem_mgis::Parameters{{“Attr1”, 1}, {“Attr2”, 2}}}

• {“Boundaries”, mfem_mgis::Parameters{{“left”, 1}, {“right”, 2}}}

Results

Key	Description
OutputFileName	Name of the output directory
OutputFieldName	Name of the field that will appear in ParaView (default: "u")
Material/Materials	List of materials; a submesh will be used instead of exporting the entire mesh
Boundary/Boundaries	List of boundaries; a submesh will be used instead of exporting the entire mesh
Verbosity	If this value is >= 1, submesh information will be displayed when using attributes

Export Integration Point Results At Nodes

• Key: ParaviewExportIntegrationPointResultsAtNodes

Example:

auto results = std::vector<mfem_mgis::Parameter>{
    "Stress", "ImposedTemperature", "HydrostaticPressure"};
problem.addPostProcessing(
    "ParaviewExportIntegrationPointResultsAtNodes",
    {{"OutputFileName", "SatohTestIntegrationPointOutput"},
     {"Materials", {"plate"}},
     {"Results", results}});

Results

Compute Mean Thermodynamic Forces

The Compute Mean Thermodynamic Forces post-processing step calculates the average stress over selected regions of the mesh.

• Key: MeanThermodynamicForces

Example: print the average stress of one inclusion into a matrix (RVE)

p.addPostProcessing(
    "MeanThermodynamicForces",
    {{"OutputFileName", "avgStress"}});

Results

We display the average stress SZZ over the RVE (composed of 83% matrix and 17% inclusion), we process the avgstress file and then plot the result:

awk '{if(NR>13) print $1 " " 0.83*$4+0.17*$10}' avgStress > res-mfem-mgis.txt
plot "res-mfem-mgis.txt" u 1:2 w l title "mfem-mgis"

Compute Stored Energy

• Key: StoredEnergy

Example:

p.addPostProcessing(
    "StoredEnergy",
    {{"OutputFileName", "energy.txt"}});

Compute dissipated Energy

• Key: DissipatedEnergy

Example:

p.addPostProcessing(
    "DissipatedEnergy",
    {{"OutputFileName", "dissiped_energy.txt"}});