Merge pull request #14607 from bwspenc/conv_flux

Add option for temperature-dependent convective heat transfer coefficient

modules/heat_conduction/doc/content/source/bcs/ConvectiveFluxFunction.md

@@ -4,9 +4,16 @@
 
 ## Description
 
-The `ConvectiveFluxFunction` boundary condition determines the value on a boundary based
-upon the heat transfer coefficient of the fluid on the outside of boundary and far-field
-temperature.
+The `ConvectiveFluxFunction` boundary condition is used to prescribe the following convective flux
+$\dot{q}$ to a boundary of a thermal model:
+\begin{equation}
+   \dot{q} = h(T(x) - T_{\text{inf}})
+\end{equation}
+where $h$ is the heat transfer coefficient, $T(x)$ is the temperature at a location $x$, where $x$ is
+the location of a given quadrature point on the surface where this boundary condition is applied, and
+$T_{\text{inf}}$ is the far-field temperature of the fluid that the boundary is exposed to.
+
+The far-field temperature is specified using the `T_infinity` parameter, which is a MOOSE Function. This can be provided as the name of a function, using a parsed function, or a constant value.  Likewise, the heat transfer coefficient is specified using the `coefficient` parameter, which is also a MOOSE Function, and the same options for how to prescribe `T_infinity` also apply for this parameter. By default, the heat transfer coefficient function is defined in terms of position and time (the standard usage of MOOSE Functions). If the optional `coefficient_function_type` parameter is set to `TEMPERATURE`, the coefficient is instead a function of the temperature. If a Function such as `PiecewiseLinear` were used to define this coefficient, the values on the x-axis of that function would be interpreted as temperature values. If a parsed function were used for this purpose, the `t` variable in a parsed equation would be used for the temperature, rather than for the time.
 
 !syntax parameters /BCs/ConvectiveFluxFunction
 

modules/heat_conduction/include/bcs/ConvectiveFluxFunction.h

@@ -20,11 +20,26 @@ class ConvectiveFluxFunction : public IntegratedBC
   virtual ~ConvectiveFluxFunction() {}
 
 protected:
-  virtual Real computeQpResidual();
-  virtual Real computeQpJacobian();
+  virtual Real computeQpResidual() override;
+  virtual Real computeQpJacobian() override;
 
+  /// Far-field temperature
   const Function & _T_infinity;
-  const Real _coefficient;
+
+  /// Heat transfer coefficient
+  const Function & _coefficient;
+
+  /// Enum used to define the type of function used for the heat transfer coefficient
+  enum class CoefFuncType
+  {
+    TIME_AND_POSITION,
+    TEMPERATURE
+  };
+
+  /// Type of function used for the heat transfer coefficient
+  const CoefFuncType _coef_func_type;
+
+  /// Heat transfer coefficient function (Deprecated -- being replaced by _coefficient)
   const Function * const _coef_func;
 };
 

modules/heat_conduction/src/bcs/ConvectiveFluxFunction.C

@@ -20,8 +20,18 @@ ConvectiveFluxFunction::validParams()
 {
   InputParameters params = IntegratedBC::validParams();
   params.addRequiredParam<FunctionName>("T_infinity", "Function describing far-field temperature");
-  params.addRequiredParam<Real>("coefficient", "Heat transfer coefficient");
-  params.addParam<FunctionName>("coefficient_function", "Heat transfer coefficient function");
+  params.addRequiredParam<FunctionName>("coefficient",
+                                        "Function describing heat transfer coefficient");
+  MooseEnum coef_func_type("TIME_AND_POSITION TEMPERATURE", "TIME_AND_POSITION");
+  params.addParam<MooseEnum>(
+      "coefficient_function_type",
+      coef_func_type,
+      "Type of function for heat transfer coefficient provided in 'coefficient' parameter");
+  params.addDeprecatedParam<FunctionName>(
+      "coefficient_function",
+      "Heat transfer coefficient function",
+      "'coefficient' should be used instead. 'coefficient_function will be removed on March 1, "
+      "2020.");
   params.addClassDescription(
       "Determines boundary value by fluid heat transfer coefficient and far-field temperature");
 
@@ -31,21 +41,46 @@ ConvectiveFluxFunction::validParams()
 ConvectiveFluxFunction::ConvectiveFluxFunction(const InputParameters & parameters)
   : IntegratedBC(parameters),
     _T_infinity(getFunction("T_infinity")),
-    _coefficient(getParam<Real>("coefficient")),
+    _coefficient(getFunction("coefficient")),
+    _coef_func_type(getParam<MooseEnum>("coefficient_function_type").getEnum<CoefFuncType>()),
     _coef_func(isParamValid("coefficient_function") ? &getFunction("coefficient_function") : NULL)
 {
+  if (_coef_func_type == CoefFuncType::TEMPERATURE && _coef_func)
+    mooseError("Deprecated 'coefficient_function' parameter cannot be used with "
+               "'coefficient_function_type=TEMPERATURE'");
 }
 
 Real
 ConvectiveFluxFunction::computeQpResidual()
 {
-  const Real coef(_coefficient * (_coef_func ? _coef_func->value(_t, _q_point[_qp]) : 1));
+  Real coef;
+  if (_coef_func_type == CoefFuncType::TIME_AND_POSITION)
+  {
+    coef = _coefficient.value(_t, _q_point[_qp]);
+    if (_coef_func) // Deprecated behavior
+      coef *= _coef_func->value(_t, _q_point[_qp]);
+  }
+  else
+    coef = _coefficient.value(_u[_qp], Point());
+
   return _test[_i][_qp] * coef * (_u[_qp] - _T_infinity.value(_t, _q_point[_qp]));
 }
 
 Real
 ConvectiveFluxFunction::computeQpJacobian()
 {
-  const Real coef(_coefficient * (_coef_func ? _coef_func->value(_t, _q_point[_qp]) : 1));
-  return _test[_i][_qp] * coef * _phi[_j][_qp];
+  if (_coef_func_type == CoefFuncType::TIME_AND_POSITION)
+  {
+    Real coef = _coefficient.value(_t, _q_point[_qp]);
+    if (_coef_func) // Deprecated behavior
+      coef *= _coef_func->value(_t, _q_point[_qp]);
+    return _test[_i][_qp] * coef * _phi[_j][_qp];
+  }
+  else
+  {
+    const Real coef = _coefficient.value(_u[_qp], Point());
+    const Real dcoef_dT = _coefficient.timeDerivative(_u[_qp], Point());
+    return _test[_i][_qp] * (coef + (_u[_qp] - _T_infinity.value(_t, _q_point[_qp])) * dcoef_dT) *
+           _phi[_j][_qp];
+  }
 }

modules/heat_conduction/test/tests/convective_flux_function/convective_flux_function.i

@@ -0,0 +1,99 @@
+# This is a test of the ConvectiveFluxFunction BC.
+# There is a single 1x1 element with a prescribed temperature
+# on the left side and a convective flux BC on the right side.
+# The temperature on the left is 100, and the far-field temp is 200.
+# The conductance of the body (conductivity * length) is 10
+#
+# If the conductance in the BC is also 10, the temperature on the
+# right side of the solid element should be 150 because half of the
+# temperature drop should occur over the body and half in the BC.
+#
+# The integrated flux is deltaT * conductance, or -50 * 10 = -500.
+# The negative sign indicates that heat is going into the body.
+#
+# The conductance is defined multiple ways using this input, and
+# as long as it evaluates to 10, the result described above will
+# be obtained.
+
+[Mesh]
+  type = GeneratedMesh
+  dim = 2
+  nx = 1
+  ny = 1
+[]
+
+[Problem]
+  extra_tag_vectors = 'bcs'
+[]
+
+[Variables]
+  [temp]
+    initial_condition = 100.0
+  []
+[]
+
+[AuxVariables]
+  [flux]
+  []
+[]
+
+[AuxKernels]
+  [flux]
+    type = TagVectorAux
+    variable = flux
+    v = temp
+    vector_tag = 'bcs'
+    execute_on = timestep_end
+  []
+[]
+
+[Kernels]
+  [heat_conduction]
+    type = HeatConduction
+    variable = temp
+  []
+[]
+
+[Materials]
+  [thermal]
+    type = HeatConductionMaterial
+    thermal_conductivity = 10.0
+  []
+[]
+
+[BCs]
+  [left]
+    type = DirichletBC
+    variable = temp
+    boundary = left
+    value = 100.0
+  []
+  [right]
+    type = ConvectiveFluxFunction
+    variable = temp
+    boundary = right
+    T_infinity = 200.0
+    coefficient = 10.0 #This will behave as described in the header of this file if this evaluates to 10
+    extra_vector_tags = 'bcs'
+  []
+[]
+
+[Postprocessors]
+  [integrated_flux]
+    type = NodalSum
+    variable = flux
+    boundary = right
+  []
+[]
+
+[Executioner]
+  type = Transient
+  start_time = 0.0
+  end_time = 1.0
+  dt = 1.0
+  nl_rel_tol=1e-12
+[]
+
+[Outputs]
+  csv = true
+[]

modules/heat_conduction/test/tests/convective_flux_function/gold/convective_flux_function_out.csv

@@ -0,0 +1,3 @@
+time,integrated_flux
+0,0
+1,-500

modules/heat_conduction/test/tests/convective_flux_function/tests

@@ -0,0 +1,26 @@
+[Tests]
+  design = 'ConvectiveFluxFunction.md'
+  issues = '#14418'
+  [./constant]
+    type = 'CSVDiff'
+    input = 'convective_flux_function.i'
+    csvdiff = 'convective_flux_function_out.csv'
+    requirement = 'The system shall allow prescribing a convective flux boundary condition using a constant heat transfer coefficient.'
+  [../]
+  [./time_dependent]
+    prereq = constant
+    type = 'CSVDiff'
+    input = 'convective_flux_function.i'
+    cli_args = "BCs/right/coefficient='t*10.0'"
+    csvdiff = 'convective_flux_function_out.csv'
+    requirement = 'The system shall allow prescribing a convective flux boundary condition using a heat transfer coefficient that is a function of position and time.'
+  [../]
+  [./temperature_dependent]
+    prereq = time_dependent
+    type = 'CSVDiff'
+    input = 'convective_flux_function.i'
+    cli_args = "BCs/right/coefficient='t/15.0' BCs/right/coefficient_function_type=TEMPERATURE"
+    csvdiff = 'convective_flux_function_out.csv'
+    requirement = 'The system shall allow prescribing a convective flux boundary condition using a heat transfer coefficient that is a function of temperature.'
+  [../]
+[]