Extend MFEMSumAux to sum over an arbitrary number of MFEMVariables

framework/doc/content/source/mfem/auxkernels/MFEMSumAux.md

@@ -8,14 +8,14 @@
 
 ## Overview
 
-AuxKernel for calculating the sum of two MFEM variables that are defined on the same finite element
-space, and storing the result in a third. Both variables may be (optionally) scaled by a real scalar
-constant prior to addition.
+AuxKernel for calculating the sum of two or more MFEM variables that are defined on the same finite
+element space, and storing the result in another. All variables may be (optionally) scaled by a real
+scalar constant prior to addition.
 
 !equation
-u = \lambda_1 v_1 + \lambda_2 v_2.
+u = \sum_i \lambda_i v_i.
 
-where $u, v_1, v_2$ are defined on the same FE space, and $\lambda_1, \lambda_2$ are real scalar
+where $u$ and $\{v_i\}$ are defined on the same FE space, and $\{\lambda_i\}$ are real scalar
 constants.
 
 ## Example Input File Syntax

framework/include/mfem/auxkernels/MFEMSumAux.h

@@ -32,14 +32,11 @@ class MFEMSumAux : public MFEMAuxKernel
 
 protected:
   // Names of input MFEMVariables to sum.
-  const VariableName & _v1_var_name;
-  const VariableName & _v2_var_name;
-  // Reference to input variable gridfunctions.
-  const mfem::ParGridFunction & _v1_var;
-  const mfem::ParGridFunction & _v2_var;
+  const std::vector<VariableName> & _var_names;
   // Scalar factors to multiply the input variables by.
-  const mfem::real_t _lambda1;
-  const mfem::real_t _lambda2;
+  const std::vector<mfem::real_t> _scale_factors;
+  // References to input variable gridfunctions.
+  std::vector<const mfem::ParGridFunction *> _summed_vars;
 };
 
 #endif

framework/src/mfem/auxkernels/MFEMSumAux.C

@@ -21,31 +21,48 @@ MFEMSumAux::validParams()
   params.addClassDescription(
       "Calculates the sum of two variables sharing an FE space, each optionally scaled by a real "
       "constant, and stores the result in a third.");
-  params.addRequiredParam<VariableName>("first_source_variable", "First variable to sum.");
-  params.addRequiredParam<VariableName>("second_source_variable", "Second variable to sum.");
-  params.addParam<mfem::real_t>(
-      "first_scale_factor", 1.0, "Factor to scale the first variable by prior to sum.");
-  params.addParam<mfem::real_t>(
-      "second_scale_factor", 1.0, "Factor to scale the second variable by prior to sum.");
+  params.addRequiredParam<std::vector<VariableName>>("source_variables",
+                                                     "The names of MFEM variables to sum over");
+  params.addParam<std::vector<mfem::real_t>>(
+      "scale_factors", "The factors to scale each MFEM variable by during summation");
   return params;
 }
 
 MFEMSumAux::MFEMSumAux(const InputParameters & parameters)
   : MFEMAuxKernel(parameters),
-    _v1_var_name(getParam<VariableName>("first_source_variable")),
-    _v2_var_name(getParam<VariableName>("second_source_variable")),
-    _v1_var(*getMFEMProblem().getProblemData().gridfunctions.Get(_v1_var_name)),
-    _v2_var(*getMFEMProblem().getProblemData().gridfunctions.Get(_v2_var_name)),
-    _lambda1(getParam<mfem::real_t>("first_scale_factor")),
-    _lambda2(getParam<mfem::real_t>("second_scale_factor"))
+    _var_names(getParam<std::vector<VariableName>>("source_variables")),
+    _scale_factors(parameters.isParamValid("scale_factors")
+                       ? getParam<std::vector<mfem::real_t>>("scale_factors")
+                       : std::vector<mfem::real_t>(_var_names.size(), 1.0))
 {
+  if (_var_names.size() != _scale_factors.size())
+    paramError("scale_factors",
+               "Number of MFEM variables to sum over is different from the number of provided "
+               "scale factors.");
+  for (const auto & var_name : _var_names)
+  {
+    const mfem::ParGridFunction * gf =
+        getMFEMProblem().getProblemData().gridfunctions.Get(var_name);
+    if (gf->ParFESpace() == _result_var.ParFESpace())
+      _summed_vars.push_back(gf);
+    else
+      paramError("source_variables",
+                 "The MFEM variable ",
+                 var_name,
+                 " being summed has a different FESpace from ",
+                 _result_var_name);
+  }
 }
 
 void
 MFEMSumAux::execute()
 {
-  // result = lambda1 * v1 + lambda2 * v2
-  add(_lambda1, _v1_var, _lambda2, _v2_var, _result_var);
+  // result = sum_i (_scale_factor_i * _summed_var_i)
+  _result_var = 0.0;
+  for (const auto i : index_range(_summed_vars))
+  {
+    _result_var.Add(_scale_factors[i], *_summed_vars[i]);
+  }
 }
 
 #endif

test/tests/mfem/submeshes/cut_closed_coil.i

@@ -141,8 +141,7 @@ coil_conductivity = 1.0
   [update_total_e_field]
     type = MFEMSumAux
     variable = e_field
-    first_source_variable = induced_e_field
-    second_source_variable = external_e_field
+    source_variables = 'induced_e_field external_e_field'
     execute_on = TIMESTEP_END
     execution_order_group = 3
   []

test/tests/mfem/submeshes/hphi_magnetostatic.i

@@ -136,8 +136,7 @@ vacuum_permeability = 1.0
   [update_total_h_field]
     type = MFEMSumAux
     variable = vacuum_h_field
-    first_source_variable = background_h_field
-    second_source_variable = cut_function_field
+    source_variables = 'background_h_field cut_function_field'
     execute_on = TIMESTEP_END
     execution_order_group = 3
   []

unit/src/MFEMAuxKernelTest.C

@@ -0,0 +1,86 @@
+//* This file is part of the MOOSE framework
+//* https://mooseframework.inl.gov
+//*
+//* All rights reserved, see COPYRIGHT for full restrictions
+//* https://github.com/idaholab/moose/blob/master/COPYRIGHT
+//*
+//* Licensed under LGPL 2.1, please see LICENSE for details
+//* https://www.gnu.org/licenses/lgpl-2.1.html
+
+#ifdef MOOSE_MFEM_ENABLED
+
+#include "MFEMObjectUnitTest.h"
+#include "MFEMSumAux.h"
+
+class MFEMAuxKernelTest : public MFEMObjectUnitTest
+{
+public:
+  MFEMAuxKernelTest() : MFEMObjectUnitTest("MooseUnitApp") {}
+};
+
+/**
+ * Test MFEMSumAux creates sums input GridFunctions successfully.
+ */
+TEST_F(MFEMAuxKernelTest, MFEMSumAux)
+{
+  // Register dummy (Par)GridFunctions to test MFEMSumAux against
+  auto pm = _mfem_mesh_ptr->getMFEMParMeshPtr().get();
+  mfem::common::H1_ParFESpace fe(pm, 1);
+  mfem::common::H1_ParFESpace different_fe(pm, 2);
+
+  auto pgf_1 = std::make_shared<mfem::ParGridFunction>(&fe);
+  auto pgf_2 = std::make_shared<mfem::ParGridFunction>(&fe);
+  auto pgf_3 = std::make_shared<mfem::ParGridFunction>(&fe);
+  auto pgf_out = std::make_shared<mfem::ParGridFunction>(&fe);
+  auto pgf_ho = std::make_shared<mfem::ParGridFunction>(&different_fe);
+
+  _mfem_problem->getProblemData().gridfunctions.Register("source_variable_1", pgf_1);
+  _mfem_problem->getProblemData().gridfunctions.Register("source_variable_2", pgf_2);
+  _mfem_problem->getProblemData().gridfunctions.Register("source_variable_3", pgf_3);
+  _mfem_problem->getProblemData().gridfunctions.Register("summed_variable", pgf_out);
+  _mfem_problem->getProblemData().gridfunctions.Register("source_ho_variable", pgf_ho);
+
+  // Initialise variables that are to be summed over
+  mfem::ConstantCoefficient initial_condition_coef(2.0);
+  pgf_1->ProjectCoefficient(initial_condition_coef);
+  pgf_2->ProjectCoefficient(initial_condition_coef);
+  pgf_3->ProjectCoefficient(initial_condition_coef);
+  pgf_ho->ProjectCoefficient(initial_condition_coef);
+
+  {
+    // Construct auxkernel
+    InputParameters auxkernel_params = _factory.getValidParams("MFEMSumAux");
+    auxkernel_params.set<AuxVariableName>("variable") = "summed_variable";
+    auxkernel_params.set<std::vector<VariableName>>("source_variables") = {
+        "source_variable_1", "source_variable_2", "source_variable_3"};
+    auxkernel_params.set<std::vector<mfem::real_t>>("scale_factors") = {1.0, 2.0, 5.0};
+
+    MFEMSumAux & auxkernel = addObject<MFEMSumAux>("MFEMSumAux", "auxkernel1", auxkernel_params);
+    auxkernel.execute();
+
+    // Check the value of the output gridfunction is the scaled sum of the components
+    ASSERT_EQ(pgf_out->GetData()[5], 16.0);
+  }
+  {
+    // Check for failure if a variable to be summed has a different FESpace from the parent
+    InputParameters auxkernel_params = _factory.getValidParams("MFEMSumAux");
+    auxkernel_params.set<AuxVariableName>("variable") = "summed_variable";
+    auxkernel_params.set<std::vector<VariableName>>("source_variables") = {
+        "source_variable_1", "source_ho_variable", "source_variable_3"};
+    auxkernel_params.set<std::vector<mfem::real_t>>("scale_factors") = {1.0, 2.0, 5.0};
+    EXPECT_THROW(addObject<MFEMSumAux>("MFEMSumAux", "failed_auxkernel", auxkernel_params),
+                 std::runtime_error);
+  }
+  {
+    // Check for failure if an inconsistent number of scale factors are provided
+    InputParameters auxkernel_params = _factory.getValidParams("MFEMSumAux");
+    auxkernel_params.set<AuxVariableName>("variable") = "summed_variable";
+    auxkernel_params.set<std::vector<VariableName>>("source_variables") = {
+        "source_variable_1", "source_variable_2", "source_variable_3"};
+    auxkernel_params.set<std::vector<mfem::real_t>>("scale_factors") = {1.0, 2.0};
+    EXPECT_THROW(addObject<MFEMSumAux>("MFEMSumAux", "failed_scaled_auxkernel", auxkernel_params),
+                 std::runtime_error);
+  }
+}
+
+#endif

unit/src/MFEMEssentialBCTest.C

@@ -1,3 +1,12 @@
+//* This file is part of the MOOSE framework
+//* https://mooseframework.inl.gov
+//*
+//* All rights reserved, see COPYRIGHT for full restrictions
+//* https://github.com/idaholab/moose/blob/master/COPYRIGHT
+//*
+//* Licensed under LGPL 2.1, please see LICENSE for details
+//* https://www.gnu.org/licenses/lgpl-2.1.html
+
 #ifdef MOOSE_MFEM_ENABLED
 
 #include "libmesh/ignore_warnings.h"

unit/src/MFEMFESpaceTest.C

@@ -1,3 +1,12 @@
+//* This file is part of the MOOSE framework
+//* https://mooseframework.inl.gov
+//*
+//* All rights reserved, see COPYRIGHT for full restrictions
+//* https://github.com/idaholab/moose/blob/master/COPYRIGHT
+//*
+//* Licensed under LGPL 2.1, please see LICENSE for details
+//* https://www.gnu.org/licenses/lgpl-2.1.html
+
 #ifdef MOOSE_MFEM_ENABLED
 
 #include "gtest/gtest.h"

unit/src/MFEMIntegratedBCTest.C

@@ -1,3 +1,12 @@
+//* This file is part of the MOOSE framework
+//* https://mooseframework.inl.gov
+//*
+//* All rights reserved, see COPYRIGHT for full restrictions
+//* https://github.com/idaholab/moose/blob/master/COPYRIGHT
+//*
+//* Licensed under LGPL 2.1, please see LICENSE for details
+//* https://www.gnu.org/licenses/lgpl-2.1.html
+
 #ifdef MOOSE_MFEM_ENABLED
 
 #include "libmesh/ignore_warnings.h"

unit/src/MFEMKernelTest.C

@@ -1,3 +1,12 @@
+//* This file is part of the MOOSE framework
+//* https://mooseframework.inl.gov
+//*
+//* All rights reserved, see COPYRIGHT for full restrictions
+//* https://github.com/idaholab/moose/blob/master/COPYRIGHT
+//*
+//* Licensed under LGPL 2.1, please see LICENSE for details
+//* https://www.gnu.org/licenses/lgpl-2.1.html
+
 #ifdef MOOSE_MFEM_ENABLED
 
 #include "MFEMObjectUnitTest.h"

unit/src/MFEMMaterialTest.C

@@ -1,3 +1,12 @@
+//* This file is part of the MOOSE framework
+//* https://mooseframework.inl.gov
+//*
+//* All rights reserved, see COPYRIGHT for full restrictions
+//* https://github.com/idaholab/moose/blob/master/COPYRIGHT
+//*
+//* Licensed under LGPL 2.1, please see LICENSE for details
+//* https://www.gnu.org/licenses/lgpl-2.1.html
+
 #ifdef MOOSE_MFEM_ENABLED
 
 #include "MFEMObjectUnitTest.h"

unit/src/MFEMMeshTest.C

@@ -1,3 +1,12 @@
+//* This file is part of the MOOSE framework
+//* https://mooseframework.inl.gov
+//*
+//* All rights reserved, see COPYRIGHT for full restrictions
+//* https://github.com/idaholab/moose/blob/master/COPYRIGHT
+//*
+//* Licensed under LGPL 2.1, please see LICENSE for details
+//* https://www.gnu.org/licenses/lgpl-2.1.html
+
 #ifdef MOOSE_MFEM_ENABLED
 
 #include "gtest/gtest.h"

unit/src/MFEMPostprocessorTest.C

@@ -1,3 +1,12 @@
+//* This file is part of the MOOSE framework
+//* https://mooseframework.inl.gov
+//*
+//* All rights reserved, see COPYRIGHT for full restrictions
+//* https://github.com/idaholab/moose/blob/master/COPYRIGHT
+//*
+//* Licensed under LGPL 2.1, please see LICENSE for details
+//* https://www.gnu.org/licenses/lgpl-2.1.html
+
 #ifdef MOOSE_MFEM_ENABLED
 
 #include "MFEMObjectUnitTest.h"

unit/src/MFEMSolverTest.C

@@ -1,3 +1,12 @@
+//* This file is part of the MOOSE framework
+//* https://mooseframework.inl.gov
+//*
+//* All rights reserved, see COPYRIGHT for full restrictions
+//* https://github.com/idaholab/moose/blob/master/COPYRIGHT
+//*
+//* Licensed under LGPL 2.1, please see LICENSE for details
+//* https://www.gnu.org/licenses/lgpl-2.1.html
+
 #ifdef MOOSE_MFEM_ENABLED
 
 #include "MFEMObjectUnitTest.h"