206 lines
7.6 KiB
Python
206 lines
7.6 KiB
Python
# ***************************************************************************
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# * Copyright (c) 2020 Sudhanshu Dubey <sudhanshu.thethunder@gmail.com> *
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# * Copyright (c) 2021 Bernd Hahnebach <bernd@bimstatik.org> *
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# * *
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# * This file is part of the FreeCAD CAx development system. *
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# * *
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# * This program is free software; you can redistribute it and/or modify *
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# * it under the terms of the GNU Lesser General Public License (LGPL) *
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# * as published by the Free Software Foundation; either version 2 of *
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# * the License, or (at your option) any later version. *
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# * for detail see the LICENCE text file. *
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# * *
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# * This program is distributed in the hope that it will be useful, *
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# * but WITHOUT ANY WARRANTY; without even the implied warranty of *
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# * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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# * GNU Library General Public License for more details. *
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# * *
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# * You should have received a copy of the GNU Library General Public *
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# * License along with this program; if not, write to the Free Software *
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# * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 *
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# * USA *
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# * *
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# ***************************************************************************
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import sys
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import FreeCAD
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from FreeCAD import Rotation
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from FreeCAD import Vector
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import Fem
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import ObjectsFem
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from . import manager
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from .manager import get_meshname
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from .manager import init_doc
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def get_information():
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return {
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"name": "Electrostatics Capacitance Two Balls",
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"meshtype": "solid",
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"meshelement": "Tet10",
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"constraints": ["electrostatic potential"],
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"solvers": ["elmer"],
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"material": "fluid",
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"equations": ["electrostatic"],
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}
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def get_explanation(header=""):
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return (
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header
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+ """
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To run the example from Python console use:
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from femexamples.equation_electrostatics_capacitance_two_balls import setup
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setup()
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See forum topic post:
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https://forum.freecad.org/viewtopic.php?f=18&t=41488&start=90#p412047
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Electrostatics equation in FreeCAD FEM-Elmer
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"""
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)
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def setup(doc=None, solvertype="elmer"):
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# init FreeCAD document
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if doc is None:
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doc = init_doc()
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# explanation object
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# just keep the following line and change text string in get_explanation method
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manager.add_explanation_obj(doc, get_explanation(manager.get_header(get_information())))
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# geometric objects
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small_sphere1 = doc.addObject("Part::Sphere", "Small_Sphere1")
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small_sphere1.Placement = FreeCAD.Placement(Vector(-1000, 0, 0), Rotation(Vector(0, 0, 1), 0))
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small_sphere1.Radius = "500 mm"
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small_sphere2 = doc.addObject("Part::Sphere", "Small_Sphere2")
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small_sphere2.Placement = FreeCAD.Placement(Vector(1000, 0, 0), Rotation(Vector(0, 0, 1), 0))
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small_sphere2.Radius = "500 mm"
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fusion = doc.addObject("Part::MultiFuse", "Fusion")
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fusion.Shapes = [small_sphere1, small_sphere2]
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large_sphere = doc.addObject("Part::Sphere", "Large_Sphere")
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large_sphere.Radius = "5000 mm"
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geom_obj = doc.addObject("Part::Cut", "Cut")
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geom_obj.Base = large_sphere
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geom_obj.Tool = fusion
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doc.recompute()
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if FreeCAD.GuiUp:
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geom_obj.ViewObject.Transparency = 75
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geom_obj.ViewObject.Document.activeView().viewAxonometric()
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geom_obj.ViewObject.Document.activeView().fitAll()
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# analysis
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analysis = ObjectsFem.makeAnalysis(doc, "Analysis")
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if FreeCAD.GuiUp:
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import FemGui
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FemGui.setActiveAnalysis(analysis)
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# solver
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if solvertype == "elmer":
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solver_obj = ObjectsFem.makeSolverElmer(doc, "SolverElmer")
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eq_electrostatic = ObjectsFem.makeEquationElectrostatic(doc, solver_obj)
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eq_electrostatic.CalculateCapacitanceMatrix = True
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eq_electrostatic.CalculateElectricEnergy = True
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eq_electrostatic.CalculateElectricField = True
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else:
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FreeCAD.Console.PrintWarning(
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"Unknown or unsupported solver type: {}. "
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"No solver object was created.\n".format(solvertype)
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)
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analysis.addObject(solver_obj)
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# material
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material_obj = ObjectsFem.makeMaterialFluid(doc, "Air")
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mat = material_obj.Material
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mat["Name"] = "Air"
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mat["Density"] = "1.204 kg/m^3"
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mat["ThermalConductivity"] = "0.02587 W/m/K"
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mat["ThermalExpansionCoefficient"] = "3.43e-3 1/K"
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mat["SpecificHeat"] = "1.01 kJ/kg/K"
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mat["ElectricalConductivity"] = "1e-12 S/m"
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mat["RelativePermeability"] = "1.0"
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mat["RelativePermittivity"] = "1.00059"
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material_obj.Material = mat
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material_obj.References = [(geom_obj, "Solid1")]
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analysis.addObject(material_obj)
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# constraint potential 1st
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name_pot1 = "ElectrostaticPotential1"
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con_elect_pot1 = ObjectsFem.makeConstraintElectrostaticPotential(doc, name_pot1)
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con_elect_pot1.References = [(geom_obj, "Face1")]
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con_elect_pot1.ElectricInfinity = True
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con_elect_pot1.PotentialEnabled = False
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analysis.addObject(con_elect_pot1)
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# constraint potential 2nd
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name_pot2 = "ElectrostaticPotential2"
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con_elect_pot2 = ObjectsFem.makeConstraintElectrostaticPotential(doc, name_pot2)
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con_elect_pot2.References = [(geom_obj, "Face2")]
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con_elect_pot2.CapacitanceBody = 1
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con_elect_pot2.CapacitanceBodyEnabled = True
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con_elect_pot2.PotentialEnabled = False
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analysis.addObject(con_elect_pot2)
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# constraint potential 3rd
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name_pot3 = "ElectrostaticPotential3"
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con_elect_pot3 = ObjectsFem.makeConstraintElectrostaticPotential(doc, name_pot3)
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con_elect_pot3.References = [(geom_obj, "Face3")]
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con_elect_pot3.CapacitanceBody = 2
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con_elect_pot3.CapacitanceBodyEnabled = True
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con_elect_pot3.PotentialEnabled = False
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analysis.addObject(con_elect_pot3)
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# mesh
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femmesh_obj = analysis.addObject(ObjectsFem.makeMeshGmsh(doc, get_meshname()))[0]
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femmesh_obj.Shape = geom_obj
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femmesh_obj.SecondOrderLinear = False
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femmesh_obj.CharacteristicLengthMax = "600 mm"
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femmesh_obj.ViewObject.Visibility = False
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# mesh_region
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mesh_region = ObjectsFem.makeMeshRegion(doc, femmesh_obj, name="MeshRegion")
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mesh_region.CharacteristicLength = "250 mm"
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mesh_region.References = [(geom_obj, "Face2"), (geom_obj, "Face3")]
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mesh_region.ViewObject.Visibility = False
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# generate the mesh
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from femmesh import gmshtools
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gmsh_mesh = gmshtools.GmshTools(femmesh_obj, analysis)
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try:
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error = gmsh_mesh.create_mesh()
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except Exception:
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error = sys.exc_info()[1]
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FreeCAD.Console.PrintError(f"Unexpected error when creating mesh: {error}\n")
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if error:
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# try to create from existing rough mesh
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from .meshes.mesh_capacitance_two_balls_tetra10 import (
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create_nodes,
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create_elements,
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)
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fem_mesh = Fem.FemMesh()
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control = create_nodes(fem_mesh)
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if not control:
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FreeCAD.Console.PrintError("Error on creating nodes.\n")
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control = create_elements(fem_mesh)
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if not control:
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FreeCAD.Console.PrintError("Error on creating elements.\n")
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femmesh_obj.FemMesh = fem_mesh
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doc.recompute()
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return doc
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