Add analytical function test and fixup bug in ElectrostaticContactCon…

…dition (idaholab#31)

modules/electromagnetics/src/interfacekernels/ElectrostaticContactCondition.C

@@ -76,10 +76,7 @@ ElectrostaticContactCondition::computeQpResidual(Moose::DGResidualType type)
   switch (type)
   {
     case Moose::Element:
-      res = 0.5 *
-            (_conductivity_secondary[_qp] * _grad_neighbor_value[_qp] * _normals[_qp] -
-             contact_conductance * (_neighbor_value[_qp] - _u[_qp])) *
-            _test[_i][_qp];
+      res = -contact_conductance * (_neighbor_value[_qp] - _u[_qp]) * _test[_i][_qp];
       break;
 
     case Moose::Neighbor:

modules/electromagnetics/test/tests/interfacekernels/analytic_solution_test.i

@@ -0,0 +1,189 @@
+# Regression test for ElectrostaticContactCondition with analytic solution
+#
+# dim = 1D
+# X = [0,2]
+# Interface at X = 1
+#
+#   stainless_steel        graphite
+# +------------------+------------------+
+#
+# Left BC: Potential = 1
+# Right BC: Potential = 0
+# Center Interface: ElectrostaticContactCondition
+#
+
+[Mesh]
+  [./line]
+    type = GeneratedMeshGenerator
+    dim = 1
+    nx = 4
+    xmax = 2
+  [../]
+  [./break]
+    type = SubdomainBoundingBoxGenerator
+    input = line
+    block_id = 1
+    block_name = 'graphite'
+    bottom_left = '1 0 0'
+    top_right = '2 0 0'
+  [../]
+  [./block_name]
+    type = RenameBlockGenerator
+    input = break
+    old_block_id = 0
+    new_block_name = 'stainless_steel'
+  [../]
+  [./interface]
+    type = SideSetsBetweenSubdomainsGenerator
+    input = block_name
+    primary_block = 'stainless_steel'
+    paired_block = 'graphite'
+    new_boundary = 'ssg_interface'
+  [../]
+[]
+
+[Variables]
+  [./potential_graphite]
+    block = graphite
+  [../]
+  [./potential_stainless_steel]
+    block = stainless_steel
+  [../]
+[]
+
+[AuxVariables]
+  [./analytic_potential_stainless_steel]
+    block = stainless_steel
+  [../]
+  [./analytic_potential_graphite]
+    block = graphite
+  [../]
+[]
+
+[Kernels]
+  [./electric_graphite]
+    type = ConductivityLaplacian
+    variable = potential_graphite
+    conductivity_coefficient = electrical_conductivity
+    block = graphite
+  [../]
+  [./electric_stainless_steel]
+    type = ConductivityLaplacian
+    variable = potential_stainless_steel
+    conductivity_coefficient = electrical_conductivity
+    block = stainless_steel
+  [../]
+[]
+
+[AuxKernels]
+  [./analytic_function_aux_stainless_steel]
+    type = FunctionAux
+    function = potential_fxn_stainless_steel
+    variable = analytic_potential_stainless_steel
+    block = stainless_steel
+  [../]
+  [./analytic_function_aux_graphite]
+    type = FunctionAux
+    function = potential_fxn_graphite
+    variable = analytic_potential_graphite
+    block = graphite
+  [../]
+[]
+
+[BCs]
+  [./elec_left]
+    type = ADDirichletBC
+    variable = potential_stainless_steel
+    boundary = left
+    value = 1
+  [../]
+  [./elec_right]
+    type = ADDirichletBC
+    variable = potential_graphite
+    boundary = right
+    value = 0
+  [../]
+[]
+
+[InterfaceKernels]
+  [./electric_contact_conductance_ssg]
+    type = ElectrostaticContactCondition
+    variable = potential_stainless_steel
+    neighbor_var = potential_graphite
+    boundary = ssg_interface
+    mean_hardness = mean_hardness
+    mechanical_pressure = 3000
+  [../]
+[]
+
+[Materials]
+  #graphite (at 300 K)
+  [./sigma_graphite]
+    type = ADGenericConstantMaterial
+    prop_names = electrical_conductivity
+    prop_values = 73069.2
+    temperature = temperature_graphite
+    block = graphite
+  [../]
+
+  #stainless_steel (at 300 K)
+  [./sigma_stainless_steel]
+    type = ADGenericConstantMaterial
+    prop_names = electrical_conductivity
+    prop_values = 1.41867e6
+    temperature = temperature_stainless_steel
+    block = stainless_steel
+  [../]
+
+  # harmonic mean of graphite and stainless steel hardness
+  [./mean_hardness]
+    type = ADGenericConstantMaterial
+    prop_names = mean_hardness
+    prop_values = 2.4797e9
+  [../]
+[]
+
+[Functions]
+  [./potential_fxn_stainless_steel]
+    type = ElectricalContactTestFunc
+    domain = stainless_steel
+  [../]
+  [./potential_fxn_graphite]
+    type = ElectricalContactTestFunc
+    domain = graphite
+  [../]
+[]
+
+[Postprocessors]
+  [./error_stainless_steel]
+    type = ElementL2Error
+    variable = potential_stainless_steel
+    function = potential_fxn_stainless_steel
+    block = stainless_steel
+  [../]
+  [./error_graphite]
+    type = ElementL2Error
+    variable = potential_graphite
+    function = potential_fxn_graphite
+    block = graphite
+  [../]
+[]
+
+
+[Preconditioning]
+  [./SMP]
+    type = SMP
+    full = true
+  [../]
+[]
+
+[Executioner]
+  type = Steady
+  solve_type = NEWTON
+  automatic_scaling = true
+[]
+
+[Outputs]
+  csv = true
+  perf_graph = true
+[]

modules/electromagnetics/test/tests/interfacekernels/gold/analytic_solution_test_out.csv

@@ -0,0 +1,3 @@
+time,error_graphite,error_stainless_steel
+0,0,0
+1,1.7691842306039e-07,9.1122582866556e-09

modules/electromagnetics/test/tests/interfacekernels/tests

@@ -50,4 +50,9 @@
     difference_tol = 2e-8   #default = 1e-8, first evaluation is 1.15647e-8
     prereq = electrostatic_contact_conductance_calculated
   [../]
+  [./electrostatic_contact_analytic_solution_test]
+    type = CSVDiff
+    input = 'analytic_solution_test.i'
+    csvdiff = 'analytic_solution_test_out.csv'
+  [../]
 []