[FEM] Elmer: fixes for electrostatics

- one needs to specify a file when calculating the capacitance matrix
- add electric flux to point filter results
- add missing parameters
- also some sorting

src/Mod/Fem/Gui/TaskPostBoxes.cpp

@@ -1136,6 +1136,9 @@ void TaskPostDataAtPoint::on_Field_activated(int i) {
     else if (FieldName == "electric energy density") {
         static_cast<Fem::FemPostDataAtPointFilter*>(getObject())->Unit.setValue("J/m^3");
     }
+    else if (FieldName == "electric flux") {
+        static_cast<Fem::FemPostDataAtPointFilter *>(getObject())->Unit.setValue("A*s/m^2");
+    }
     // ToDo: set a proper unit once it is known
     else if (FieldName == "potential loads") {
         static_cast<Fem::FemPostDataAtPointFilter*>(getObject())->Unit.setValue("");

src/Mod/Fem/femsolver/elmer/equations/electrostatic.py

@@ -44,6 +44,19 @@ class Proxy(linear.Proxy, equationbase.ElectrostaticProxy):
 
     def __init__(self, obj):
         super(Proxy, self).__init__(obj)
+        
+        obj.addProperty(
+            "App::PropertyBool",
+            "CalculateCapacitanceMatrix",
+            "Electrostatic",
+            ""
+        )
+        obj.addProperty(
+            "App::PropertyBool",
+            "CalculateElectricEnergy",
+            "Electrostatic",
+            ""
+        )
         obj.addProperty(
             "App::PropertyBool",
             "CalculateElectricField",
@@ -56,24 +69,12 @@ class Proxy(linear.Proxy, equationbase.ElectrostaticProxy):
             "Electrostatic",
             ""
         )
-        obj.addProperty(
-            "App::PropertyBool",
-            "CalculateElectricEnergy",
-            "Electrostatic",
-            ""
-        )
         obj.addProperty(
             "App::PropertyBool",
             "CalculateSurfaceCharge",
             "Electrostatic",
             ""
         )
-        obj.addProperty(
-            "App::PropertyBool",
-            "CalculateCapacitanceMatrix",
-            "Electrostatic",
-            ""
-        )
         """
         obj.addProperty(
             "App::PropertyInteger",
@@ -82,7 +83,33 @@ class Proxy(linear.Proxy, equationbase.ElectrostaticProxy):
             ""
         )
         """
+        obj.addProperty(
+            "App::PropertyFile",
+            "CapacitanceMatrixFilename",
+            "Electrostatic",
+            (
+                "File where capacitance matrix is being saved\n"
+                "Only used if 'CalculateCapacitanceMatrix' is true"
+            )
+        )
+        obj.addProperty(
+            "App::PropertyBool",
+            "ConstantWeights",
+            "Electrostatic",
+            "Use constant weighting for results"
+        )
+        obj.addProperty(
+            "App::PropertyFloat",
+            "PotentialDifference",
+            "Electrostatic",
+            (
+                "Potential difference in Volt for which capacitance is\n"
+                "calculated if 'CalculateCapacitanceMatrix' is false"
+            )
+        )
 
+        obj.CapacitanceMatrixFilename = "cmatrix.dat"
+        obj.PotentialDifference = 0.0
         obj.Priority = 10
 
 

src/Mod/Fem/femsolver/elmer/writer.py

@@ -557,22 +557,67 @@ class Writer(object):
             self._handleElectrostaticMaterial(activeIn)
 
     def _getElectrostaticSolver(self, equation):
+        # check if we need to update the equation
+        self._updateElectrostaticSolver(equation)
+        # output the equation parameters
         s = self._createLinearSolver(equation)
         s["Equation"] = "Stat Elec Solver"  # equation.Name
         s["Procedure"] = sifio.FileAttr("StatElecSolve/StatElecSolver")
         s["Variable"] = self._getUniqueVarName("Potential")
         s["Variable DOFs"] = 1
-        s["Calculate Electric Field"] = equation.CalculateElectricField
-        # s["Calculate Electric Flux"] = equation.CalculateElectricFlux
-        s["Calculate Electric Energy"] = equation.CalculateElectricEnergy
-        s["Calculate Surface Charge"] = equation.CalculateSurfaceCharge
-        s["Calculate Capacitance Matrix"] = equation.CalculateCapacitanceMatrix
-        s["Displace mesh"] = False
+        if equation.CalculateCapacitanceMatrix is True:
+            s["Calculate Capacitance Matrix"] = equation.CalculateCapacitanceMatrix
+            s["Capacitance Matrix Filename"] = equation.CapacitanceMatrixFilename
+        if equation.CalculateElectricEnergy is True:
+            s["Calculate Electric Energy"] = equation.CalculateElectricEnergy
+        if equation.CalculateElectricField is True:
+            s["Calculate Electric Field"] = equation.CalculateElectricField
+        if equation.CalculateElectricFlux is True:
+            s["Calculate Electric Flux"] = equation.CalculateElectricFlux
+        if equation.CalculateSurfaceCharge is True:
+            s["Calculate Surface Charge"] = equation.CalculateSurfaceCharge
+        if equation.ConstantWeights is True:
+            s["Constant Weights"] = equation.ConstantWeights
         s["Exec Solver"] = "Always"
         s["Optimize Bandwidth"] = True
+        if equation.CalculateCapacitanceMatrix is False\
+            and (equation.PotentialDifference != 0.0):
+            s["Potential Difference"] = equation.PotentialDifference
         s["Stabilize"] = equation.Stabilize
         return s
 
+    def _updateElectrostaticSolver(self, equation):
+        # updates older Electrostatic equations
+        if not hasattr(equation, "CapacitanceMatrixFilename"):
+            equation.addProperty(
+                "App::PropertyFile",
+                "CapacitanceMatrixFilename",
+                "Electrostatic",
+                (
+                    "File where capacitance matrix is being saved\n"
+                    "Only used if 'CalculateCapacitanceMatrix' is true"
+                )
+            )
+            equation.CapacitanceMatrixFilename = "cmatrix.dat"
+        if not hasattr(equation, "ConstantWeights"):
+            equation.addProperty(
+                "App::PropertyBool",
+                "ConstantWeights",
+                "Electrostatic",
+                "Use constant weighting for results"
+            )
+        if not hasattr(equation, "PotentialDifference"):
+            equation.addProperty(
+                "App::PropertyFloat",
+                "PotentialDifference",
+                "Electrostatic",
+                (
+                    "Potential difference in Volt for which capacitance is\n"
+                    "calculated if 'CalculateCapacitanceMatrix' is false"
+                )
+            )
+            equation.PotentialDifference = 0.0
+
     def _handleElectrostaticConstants(self):
         self._constant(
             "Permittivity Of Vacuum",