[FEM] fix wrong console outputs for fluid materials

- since a while ThermalExpansionCoefficient is used, VolumetricThermalExpansionCoefficient is only used for the material task panel
- as already stated in a code comment, the unit of VolumetricThermalExpansionCoefficient is ThermalExpansionCoefficient, therefore we must check for ThermalExpansionCoefficient
- we must also check if ThermalExpansionCoefficient exists

- Adapt the existing fluid material cards to use the ThermalExpansionCoefficient

src/Mod/Fem/femtaskpanels/task_material_common.py

@@ -461,22 +461,36 @@ class _TaskPanel:
                     .format(self.material["Name"])
                 )
                 self.material["KinematicViscosity"] = "0 m^2/s"
+            if "ThermalExpansionCoefficient" in self.material:
+                vol_ther_ex_co = self.material["ThermalExpansionCoefficient"]
+                if "ThermalExpansionCoefficient" not in str(Units.Unit(vol_ther_ex_co)):
+                    FreeCAD.Console.PrintMessage(
+                        "ThermalExpansionCoefficient in material data "
+                        "seems to have no unit or a wrong unit (reset the value): {}\n"
+                        .format(self.material["Name"])
+                    )
+                    self.material["ThermalExpansionCoefficient"] = "0 1/K"
+            else:
+                FreeCAD.Console.PrintMessage(
+                    "ThermalExpansionCoefficient not found in {}\n"
+                    .format(self.material["Name"])
+                )
+                self.material["VolumetricThermalExpansionCoefficient"] = "0 1/K"
             if "VolumetricThermalExpansionCoefficient" in self.material:
                 # unit type VolumetricThermalExpansionCoefficient is ThermalExpansionCoefficient
                 vol_ther_ex_co = self.material["VolumetricThermalExpansionCoefficient"]
-                if "VolumetricThermalExpansionCoefficient" not in str(Units.Unit(vol_ther_ex_co)):
+                if "ThermalExpansionCoefficient" not in str(Units.Unit(vol_ther_ex_co)):
                     FreeCAD.Console.PrintMessage(
                         "VolumetricThermalExpansionCoefficient in material data "
                         "seems to have no unit or a wrong unit (reset the value): {}\n"
                         .format(self.material["Name"])
                     )
-                    self.material["VolumetricThermalExpansionCoefficient"] = "0 m^3/m^3/K"
+                    self.material["VolumetricThermalExpansionCoefficient"] = "0 1/K"
             else:
-                FreeCAD.Console.PrintMessage(
-                    "VolumetricThermalExpansionCoefficient not found in {}\n"
-                    .format(self.material["Name"])
-                )
-                self.material["VolumetricThermalExpansionCoefficient"] = "0 m^3/m^3/K"
+                if "ThermalExpansionCoefficient" in self.material:
+                    self.material["VolumetricThermalExpansionCoefficient"] = self.material["ThermalExpansionCoefficient"]
+                else:
+                    self.material["VolumetricThermalExpansionCoefficient"] = "0 1/K"
         # Thermal properties
         if "ThermalConductivity" in self.material:
             # TODO implement for all task panel values

src/Mod/Material/FluidMaterial/Air.FCMat

@@ -14,8 +14,8 @@ PrandtlNumber = 0.7
 [Thermal]
 SpecificHeat = 1.01 kJ/kg/K
 ThermalConductivity = 0.02587 W/m/K
-; volumetric expansion coeff of ideal gas depends on temperature and pressure
-VolumetricThermalExpansionCoefficient = 3.43e-3 m/m/K
+; thermal expansion coefficient of ideal gas is 1/temperature
+ThermalExpansionCoefficient = 3.43e-3 1/K
 
 [Electrical]
 RelativePermittivity = 1.00059

src/Mod/Material/FluidMaterial/Argon.FCMat

@@ -15,8 +15,8 @@ PrandtlNumber = 0.7
 [Thermal]
 SpecificHeat = 0.520 kJ/kg/K
 ThermalConductivity = 0.018 W/m/K
-; volumetric expansion coeff of ideal gas depends on temperature and pressure
-VolumetricThermalExpansionCoefficient = 3.43e-3 1/K
+; thermal expansion coefficient of ideal gas is 1/temperature
+ThermalExpansionCoefficient = 3.43e-3 1/K
 
 [Electrical]
 RelativePermittivity = 1.000513

src/Mod/Material/FluidMaterial/Nitrogen.FCMat

@@ -15,8 +15,8 @@ PrandtlNumber = 0.7
 [Thermal]
 SpecificHeat = 1.04 kJ/kg/K
 ThermalConductivity = 25.83e-3 W/m/K
-; volumetric expansion coeff of ideal gas depends on temperature and pressure
-VolumetricThermalExpansionCoefficient = 3.43e-3 1/K
+; thermal expansion coefficient of ideal gas is 1/temperature
+ThermalExpansionCoefficient = 3.43e-3 1/K
 
 [Electrical]
 RelativePermittivity = 1.00058

src/Mod/Material/FluidMaterial/None.FCMat

@@ -12,5 +12,4 @@ KinematicViscosity = 0 m^2/s
 [Thermal]
 SpecificHeat = 0 J/kg/K
 ThermalConductivity = 0 W/m/K
-ThermalExpansionCoefficient = 0 um/m/K
-VolumetricThermalExpansionCoefficient = 0 m/m/K
+ThermalExpansionCoefficient = 0 1/K