From 55ac4bdb3bfa088cd8d3265be2be9aa5ee5882da Mon Sep 17 00:00:00 2001
From: Daniel Schwen <daniel.schwen@inl.gov>
Date: Mon, 20 Jan 2020 16:24:08 -0700
Subject: [PATCH] Initial conditions (#401)

---
 include/userobjects/FFTBufferBase.h |  3 ++
 src/userobjects/FFTBufferBase.C     | 58 ++++++++++++++++++++---------
 2 files changed, 44 insertions(+), 17 deletions(-)

diff --git a/include/userobjects/FFTBufferBase.h b/include/userobjects/FFTBufferBase.h
index b328fe43..89a9e907 100644
--- a/include/userobjects/FFTBufferBase.h
+++ b/include/userobjects/FFTBufferBase.h
@@ -70,4 +70,7 @@ class FFTBufferBase : public GeneralUserObject
 
   /// stride in units of double size
   std::ptrdiff_t _stride;
+
+  /// optional moose sister variabe (to obtain IC from)
+  MooseVariable * _moose_variable;
 };
diff --git a/src/userobjects/FFTBufferBase.C b/src/userobjects/FFTBufferBase.C
index 44d77ce6..dbbc6cc2 100644
--- a/src/userobjects/FFTBufferBase.C
+++ b/src/userobjects/FFTBufferBase.C
@@ -5,6 +5,7 @@
 /*            Copyright 2017 Battelle Energy Alliance, LLC            */
 /*                        ALL RIGHTS RESERVED                         */
 /**********************************************************************/
+
 #include "FFTBufferBase.h"
 #include "MooseTypes.h"
 #include "MyTRIMMesh.h"
@@ -14,15 +15,6 @@
 
 #include <type_traits>
 
-// template <>
-// InputParameters
-// validParams<FFTBufferBase>()
-// {
-//   InputParameters params = validParams<GeneralUserObject>();
-//   params.addClassDescription("");
-//   return params;
-// }
-
 template <typename T>
 InputParameters
 FFTBufferBase<T>::validParams()
@@ -34,8 +26,13 @@ FFTBufferBase<T>::validParams()
       "grid > 0",
       "Number of grid cells in each dimension to compute "
       "the FFT on (can be omitted when using MyTRIMMesh)");
-  params.addParam<unsigned int>(
-      "max_h_level", 0, "Further grid refinement to apply when using MyTRIMMesh with adaptivity");
+  if (std::is_same<T, Real>::value)
+    params.addParam<AuxVariableName>(
+        "moose_variable", "Optional AuxVariable to take the initial condition of the buffer from.");
+
+  // make sure we run the object on initial to apply the initial conditions
+  params.set<ExecFlagEnum>("execute_on") = EXEC_INITIAL;
+
   return params;
 }
 
@@ -45,8 +42,8 @@ FFTBufferBase<T>::FFTBufferBase(const InputParameters & parameters)
     _mesh(_subproblem.mesh()),
     _dim(_mesh.dimension()),
     _cell_volume(1.0),
-    _buffer_size(1)
-
+    _buffer_size(1),
+    _moose_variable(nullptr)
 {
   // make sure Real is double
   static_assert(
@@ -56,6 +53,12 @@ FFTBufferBase<T>::FFTBufferBase(const InputParameters & parameters)
   // FFT needs a regular grid of values to operate on
   if (isParamValid("grid"))
   {
+    // cannot specify a corresponding MOOSE Variable when running mesh-less
+    if (isParamValid("moose_variable"))
+      paramError("moose_variable",
+                 "You cannot specify a corresponding MOOSE Variable when running mesh-less, i.e. "
+                 "using the 'grid' parameter.");
+
     // if valid use the user-supplied sampling grid
     _grid = getParam<std::vector<int>>("grid");
     if (_grid.size() != _dim)
@@ -72,10 +75,24 @@ FFTBufferBase<T>::FFTBufferBase(const InputParameters & parameters)
       _grid.push_back(mytrim_mesh->getCellCountInDimension(i));
   }
 
-  // refine grid by max_h_level powers of two
-  auto max_h_level = getParam<unsigned int>("max_h_level");
-  for (auto & count : _grid)
-    count = count << max_h_level;
+  // check optional coupled MOOSE variable (only for Real valued buffers)
+  if (std::is_same<T, Real>::value && isParamValid("moose_variable"))
+  {
+    auto name = getParam<AuxVariableName>("moose_variable");
+    if (!_subproblem.hasVariable(name))
+      paramError("moose_variable", "Variable '", name, "' does not exist.");
+
+    // get variable
+    _moose_variable = dynamic_cast<MooseVariable *>(&_subproblem.getVariable(
+        0, name, Moose::VarKindType::VAR_AUXILIARY, Moose::VarFieldType::VAR_FIELD_STANDARD));
+    if (!_moose_variable)
+      paramError(
+          "moose_variable", "Variable '", name, "' is not a regular auxiliary field variable.");
+    if (_moose_variable->order() != 0)
+      paramError("moose_variable", "Variable '", name, "' needs to have CONSTANT order.");
+    if (_moose_variable->isNodal())
+      paramError("moose_variable", "Variable '", name, "' must be elemental.");
+  }
 
   // get mesh extents and calculate space required and estimate spectrum bins
   for (unsigned int i = 0; i < _dim; ++i)
@@ -98,6 +115,13 @@ FFTBufferBase<T>::FFTBufferBase(const InputParameters & parameters)
   istride /= sizeof(Real);
 }
 
+template <>
+void
+FFTBufferBase<Real>::initialize()
+{
+  mooseInfo("Real valued buffer");
+}
+
 template <>
 Real *
 FFTBufferBase<Real>::start(std::size_t i)