FEM: examples, added new cube capacitor example

Author: Sudhanshu-Dubey14

src/Mod/Fem/CMakeLists.txt

@@ -77,6 +77,7 @@ SET(FemExamples_SRCS
     femexamples/examplesgui.py
     femexamples/elmer_nonguitutorial01_eigenvalue_of_elastic_beam.py
     femexamples/equation_electrostatics_capacitance_two_balls.py
+    femexamples/equation_electrostatics_cube_capacitor.py
     femexamples/equation_electrostatics_electricforce_elmer_nongui6.py
     femexamples/frequency_beamsimple.py
     femexamples/manager.py
@@ -116,6 +117,7 @@ SET(FemExampleMeshes_SRCS
     femexamples/meshes/mesh_constraint_tie_tetra10.py
     femexamples/meshes/mesh_contact_box_halfcylinder_tetra10.py
     femexamples/meshes/mesh_contact_tube_tube_tria3.py
+    femexamples/meshes/mesh_cube_capacitor_tetra10.py
     femexamples/meshes/mesh_eigenvalue_of_elastic_beam_tetra10.py
     femexamples/meshes/mesh_electricforce_elmer_nongui6_tetra10.py
     femexamples/meshes/mesh_flexural_buckling.py

src/Mod/Fem/femexamples/equation_electrostatics_cube_capacitor.py

@@ -0,0 +1,138 @@
+# ***************************************************************************
+# *   Copyright (c) 2020 Sudhanshu Dubey <sudhanshu.thethunder@gmail.com>   *
+# *                                                                         *
+# *   This file is part of the FreeCAD CAx development system.              *
+# *                                                                         *
+# *   This program is free software; you can redistribute it and/or modify  *
+# *   it under the terms of the GNU Lesser General Public License (LGPL)    *
+# *   as published by the Free Software Foundation; either version 2 of     *
+# *   the License, or (at your option) any later version.                   *
+# *   for detail see the LICENCE text file.                                 *
+# *                                                                         *
+# *   This program is distributed in the hope that it will be useful,       *
+# *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+# *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+# *   GNU Library General Public License for more details.                  *
+# *                                                                         *
+# *   You should have received a copy of the GNU Library General Public     *
+# *   License along with this program; if not, write to the Free Software   *
+# *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  *
+# *   USA                                                                   *
+# *                                                                         *
+# ***************************************************************************
+
+# to run the example use:
+"""
+from femexamples.equation_electrostatics_cube_capacitor import setup
+setup()
+"""
+# Electrostatics Cube Capacitor
+# https://forum.freecadweb.org/viewtopic.php?f=18&t=41488&start=60#p401652
+
+import FreeCAD
+
+import Fem
+import ObjectsFem
+
+mesh_name = "Mesh"  # needs to be Mesh to work with unit tests
+
+
+def init_doc(doc=None):
+    if doc is None:
+        doc = FreeCAD.newDocument()
+    return doc
+
+
+def get_information():
+    info = {"name": "Electrostatics Cube Capacitor",
+            "meshtype": "solid",
+            "meshelement": "Tet10",
+            "constraints": ["electrostatic potential"],
+            "solvers": ["elmer"],
+            "material": "fluid",
+            "equation": "electrostatic"
+            }
+    return info
+
+
+def setup(doc=None, solvertype="elmer"):
+    # setup base model
+
+    if doc is None:
+        doc = init_doc()
+
+    # geometry object
+    # name is important because the other method in this module use obj name
+    geom_obj = doc.addObject("Part::Box", "Box")
+    geom_obj.Height = geom_obj.Width = geom_obj.Length = 1000
+    doc.recompute()
+
+    if FreeCAD.GuiUp:
+        geom_obj.ViewObject.Document.activeView().viewAxonometric()
+        geom_obj.ViewObject.Document.activeView().fitAll()
+
+    # analysis
+    analysis = ObjectsFem.makeAnalysis(doc, "Analysis")
+
+    # solver
+    if solvertype == "elmer":
+        solver_object = analysis.addObject(ObjectsFem.makeSolverElmer(doc, "SolverElmer"))[0]
+        eq_electrostatic = ObjectsFem.makeEquationElectrostatic(doc, solver_object)
+        eq_electrostatic.CalculateCapacitanceMatrix = True
+    else:
+        FreeCAD.Console.PrintWarning(
+            "Not known or not supported solver type: {}. "
+            "No solver object was created.\n".format(solvertype)
+        )
+
+    # material
+    material_object = analysis.addObject(
+        ObjectsFem.makeMaterialFluid(doc, "FemMaterial")
+    )[0]
+    mat = material_object.Material
+    mat["Name"] = "Air-Generic"
+    mat["Density"] = "1.20 kg/m^3"
+    mat["KinematicViscosity"] = "15.11 mm^2/s"
+    mat["VolumetricThermalExpansionCoefficient"] = "0.00 µm/m/K"
+    mat["ThermalConductivity"] = "0.03 W/m/K"
+    mat["ThermalExpansionCoefficient"] = "0.0034/K"
+    mat["SpecificHeat"] = "1.00 J/kg/K"
+    mat["RelativePermittivity"] = "1.00"
+    material_object.Material = mat
+
+    # 1st potential_constraint
+    constraint_elect_pot0 = analysis.addObject(
+        ObjectsFem.makeConstraintElectrostaticPotential(doc))[0]
+    constraint_elect_pot0.References = [(geom_obj, "Face6")]
+    constraint_elect_pot0.PotentialEnabled = True
+    constraint_elect_pot0.Potential = 2.00
+    constraint_elect_pot0.CapacitanceBodyEnabled = True
+    constraint_elect_pot0.CapacitanceBody = 1
+
+    # 2nd potential_constraint
+    constraint_elect_pot1 = analysis.addObject(
+        ObjectsFem.makeConstraintElectrostaticPotential(doc))[0]
+    constraint_elect_pot1.References = [(geom_obj, "Face5")]
+    constraint_elect_pot1.PotentialEnabled = True
+    constraint_elect_pot1.Potential = -1.00
+    constraint_elect_pot1.CapacitanceBodyEnabled = True
+    constraint_elect_pot1.CapacitanceBody = 2
+
+    # mesh
+    from .meshes.mesh_cube_capacitor_tetra10 import create_nodes, create_elements
+    fem_mesh = Fem.FemMesh()
+    control = create_nodes(fem_mesh)
+    if not control:
+        FreeCAD.Console.PrintError("Error on creating nodes.\n")
+    control = create_elements(fem_mesh)
+    if not control:
+        FreeCAD.Console.PrintError("Error on creating elements.\n")
+    femmesh_obj = analysis.addObject(
+        ObjectsFem.makeMeshGmsh(doc, mesh_name)
+    )[0]
+    femmesh_obj.FemMesh = fem_mesh
+    femmesh_obj.Part = geom_obj
+    femmesh_obj.SecondOrderLinear = False
+
+    doc.recompute()
+    return doc