Added convection to HSCoupler2D3D

Closes #27830

modules/thermal_hydraulics/doc/content/source/components/HSCoupler2D3D.md

@@ -1,7 +1,7 @@
 # HSCoupler2D3D
 
 This component is used to couple a [HeatStructureCylindrical.md] and a
-[HeatStructureFromFile3D.md] via gap conduction and radiation.
+[HeatStructureFromFile3D.md] via gap conduction, radiation, and convection.
 
 ## Formulation
 
@@ -34,10 +34,10 @@ where
 
 This approach guarantees energy conservation of this heat exchange.
 
-The heat flux is composed of two pieces, corresponding to conduction and radiation:
+The heat flux is composed of three pieces, corresponding to conduction, radiation, and convection:
 
 !equation
-q_{z,\theta} = q^\text{cond}_{z,\theta} + q^\text{rad}_{z,\theta} \,.
+q_{z,\theta} = q^\text{cond}_{z,\theta} + q^\text{rad}_{z,\theta} + q^\text{conv}_{r,\theta} \,.
 
 Before describing these pieces, we describe some preliminaries.
 
@@ -116,6 +116,18 @@ q^\text{rad}_{z,\theta} = \frac{\sigma (T_z^4 - T_{z,\theta}^4)}{\mathcal{R}_{z,
 
 where $\sigma$ is the Stefan-Boltzmann constant.
 
+### Convection Heat Flux
+
+The convection heat flux is computed as
+
+!equation
+q^\text{conv}_{z,\theta} = h^\text{gap}_{z,\theta} (T_z^4 - T_{z,\theta}^4) \,,
+
+where the gap heat transfer coefficient is evaluated at the gap temperature:
+
+!equation
+h^\text{gap}_{z,\theta} = h_\text{gap}(T^\text{gap}_{z,\theta}) \,.
+
 ## Restrictions and Assumptions
 
 - Currently, no contact ($\delta = 0$) is permitted, but this restriction is
@@ -135,15 +147,17 @@ corresponding to each heat structure, at which the heat exchange occurs.
 
 The parameters [!param](/Components/HSCoupler2D3D/emissivity_2d),
 [!param](/Components/HSCoupler2D3D/emissivity_3d),
-[!param](/Components/HSCoupler2D3D/gap_thickness), and
-[!param](/Components/HSCoupler2D3D/gap_thermal_conductivity) correspond
+[!param](/Components/HSCoupler2D3D/gap_thickness),
+[!param](/Components/HSCoupler2D3D/gap_thermal_conductivity), and
+[!param](/Components/HSCoupler2D3D/gap_htc) correspond
 to [Functions](Functions/index.md) of the relevant temperature; respectively,
 these correspond to
 
 - $\epsilon_\text{2D}(T_\text{2D})$,
 - $\epsilon_\text{3D}(T_\text{3D})$,
-- $\delta(T_\text{gap})$, and
-- $k_\text{gap}(T_\text{gap})$.
+- $\delta(T_\text{gap})$,
+- $k_\text{gap}(T_\text{gap})$, and
+- $h_\text{gap}(T_\text{gap})$.
 
 The temperature values are substituted in place of the time coordinate for
 these `Function`s.

modules/thermal_hydraulics/include/userobjects/HSCoupler2D3DUserObject.h

@@ -61,6 +61,8 @@ class HSCoupler2D3DUserObject : public SideUserObject
   const Function & _gap_thickness_fn;
   /// Gap thermal conductivity as a function of temperature
   const Function & _k_gap_fn;
+  /// Gap heat transfer coefficient as a function of temperature
+  const Function & _htc_gap_fn;
 
   /// User object containing the temperature values on the 2D boundary
   const StoreVariableByElemIDSideUserObject & _temperature_2d_uo;

modules/thermal_hydraulics/src/components/HSCoupler2D3D.C

@@ -39,6 +39,8 @@ HSCoupler2D3D::validParams()
   params.addRequiredParam<FunctionName>(
       "gap_thermal_conductivity",
       "Gap thermal conductivity [W/(m-K)] as a function of temperature [K]");
+  params.addParam<FunctionName>(
+      "gap_htc", 0, "Gap heat transfer coefficient [W/(m^2-K)] as a function of temperature [K]");
 
   params.addClassDescription("Couples a 2D heat structure boundary to a 3D heat structure boundary "
                              "using gap heat transfer.");
@@ -183,6 +185,7 @@ HSCoupler2D3D::addMooseObjects()
     params.set<FunctionName>("gap_thickness") = getParam<FunctionName>("gap_thickness");
     params.set<FunctionName>("gap_thermal_conductivity") =
         getParam<FunctionName>("gap_thermal_conductivity");
+    params.set<FunctionName>("gap_htc") = getParam<FunctionName>("gap_htc");
     params.set<UserObjectName>("temperature_2d_uo") = temperature_2d_uo_name;
     params.set<MeshAlignment2D3D *>("mesh_alignment") = &_mesh_alignment;
     params.set<ExecFlagEnum>("execute_on") = {EXEC_INITIAL, EXEC_LINEAR, EXEC_NONLINEAR};

modules/thermal_hydraulics/src/userobjects/HSCoupler2D3DUserObject.C

@@ -36,6 +36,8 @@ HSCoupler2D3DUserObject::validParams()
   params.addRequiredParam<FunctionName>(
       "gap_thermal_conductivity",
       "Gap thermal conductivity [W/(m-K)] as a function of temperature [K]");
+  params.addParam<FunctionName>(
+      "gap_htc", 0, "Gap heat transfer coefficient [W/(m^2-K)] as a function of temperature [K]");
   params.addRequiredParam<UserObjectName>(
       "temperature_2d_uo",
       "StoreVariableByElemIDSideUserObject containing the temperature values on the 2D boundary");
@@ -56,6 +58,7 @@ HSCoupler2D3DUserObject::HSCoupler2D3DUserObject(const InputParameters & paramet
     _include_radiation(isParamSetByUser("emissivity_2d") && isParamSetByUser("emissivity_3d")),
     _gap_thickness_fn(getFunction("gap_thickness")),
     _k_gap_fn(getFunction("gap_thermal_conductivity")),
+    _htc_gap_fn(getFunction("gap_htc")),
     _temperature_2d_uo(getUserObject<StoreVariableByElemIDSideUserObject>("temperature_2d_uo")),
     _mesh_alignment(*getParam<MeshAlignment2D3D *>("mesh_alignment"))
 {
@@ -102,6 +105,9 @@ HSCoupler2D3DUserObject::execute()
         HeatTransferModels::cylindricalGapConductionHeatFlux(k_gap, _r_2d, r_3d, T_2d, T_3d);
     auto heat_flux = heat_flux_cond;
 
+    const auto htc = evaluateTemperatureFunction(_htc_gap_fn, T_gap);
+    heat_flux += htc * (T_2d - T_3d);
+
     if (_include_radiation)
     {
       const auto emissivity_2d = evaluateTemperatureFunction(_emissivity_2d_fn, T_2d);

modules/thermal_hydraulics/test/tests/components/hs_coupler_2d3d/tests

@@ -31,6 +31,16 @@
       exodiff = conduction_only.e
       detail = 'using conduction only.'
     []
+    [convection_only]
+      type = Exodiff
+      input = hs_coupler_2d3d.i
+      cli_args = "
+        Components/hs_coupler/gap_thermal_conductivity=0
+        Components/hs_coupler/gap_htc=100
+        Outputs/file_base=convection_only"
+      exodiff = convection_only.e
+      detail = 'using convection only.'
+    []
   []
 
   [error_reporting]