MFEMPostprocessor

Summary

Base class for MFEM postprocessors used to evaluate a single scalar.

Overview

MFEM postprocessors calculate scalar quantities from the (aux)variables, typically after each timestep.

An MFEMPostprocessor is derived from MFEMGeneralUserObject. Therefore, the order of their execution can be controlled similar to other MOOSE UserObjects using the execution_order_group input parameter, e.g., to require the execution of a postprocessor computing on an AuxVariable strictly after the execution of the MFEMAuxKernel computing the variable field itself. For example:

[AuxKernels<<<{"href": "../../../syntax/AuxKernels/index.html"}>>>]
  [grad]
    type = MFEMGradAux<<<{"description": "Calculates the gradient of an H1 conforming source variable and stores the result on an H(curl) conforming ND result auxvariable", "href": "../auxkernels/MFEMGradAux.html"}>>>
    variable<<<{"description": "The name of the variable that this object applies to"}>>> = velocity
    source<<<{"description": "Scalar H1 MFEMVariable to take the gradient of."}>>> = velocity_potential
    execute_on<<<{"description": "The list of flag(s) indicating when this object should be executed. For a description of each flag, see https://mooseframework.inl.gov/source/interfaces/SetupInterface.html."}>>> = TIMESTEP_END
  []
[]

[Postprocessors<<<{"href": "../../../syntax/Postprocessors/index.html"}>>>]
  [velocity_error]
    type = MFEMVectorL2Error<<<{"description": "Computes L2 error $\\left\\Vert \\vec u_{ex} - \\vec u_{h}\\right\\Vert_{\\rm L2}$ for vector gridfunctions.", "href": "MFEMVectorL2Error.html"}>>>
    variable<<<{"description": "Name of the vector variable of which to find the norm of the error."}>>> = velocity
    function<<<{"description": "The analytic solution to compare against. A functor is any of the following: a variable, an MFEM material property, a function, a postprocessor or a numeric vector value (enclosed in curly braces)."}>>> = exact_velocity
    execution_order_group<<<{"description": "Execution order groups are executed in increasing order (e.g., the lowest number is executed first). Note that negative group numbers may be used to execute groups before the default (0) group. Please refer to the user object documentation for ordering of user object execution within a group."}>>> = 1
  []
[]
(test/tests/mfem/kernels/irrotational.i)

MFEMPostprocessor is a purely virtual base class. Derived classes should override the execute and getValue methods.