Merge pull request #20007 from FEA-eng/fem_example_joule_heating

FEM: Add Joule heating to FEM Examples

src/Mod/Fem/CMakeLists.txt

@@ -86,6 +86,7 @@ SET(FemExamples_SRCS
     femexamples/equation_magnetodynamics_elmer.py
     femexamples/equation_magnetodynamics_2D_elmer.py
     femexamples/equation_magnetostatics_2D_elmer.py
+    femexamples/equation_staticcurrent_elmer.py
     femexamples/frequency_beamsimple.py
     femexamples/manager.py
     femexamples/material_multiple_bendingbeam_fiveboxes.py

src/Mod/Fem/femexamples/equation_staticcurrent_elmer.py

@@ -0,0 +1,172 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+
+# ***************************************************************************
+# *   Copyright (c) 2025 Jakub Michalski <jakub.j.michalski[at]gmail.com>         *
+# *                                                                         *
+# *   This file is part of FreeCAD.                                         *
+# *                                                                         *
+# *   FreeCAD is free software: you can redistribute it and/or modify it    *
+# *   under the terms of the GNU Lesser General Public License as           *
+# *   published by the Free Software Foundation, either version 2.1 of the  *
+# *   License, or (at your option) any later version.                       *
+# *                                                                         *
+# *   FreeCAD 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      *
+# *   Lesser General Public License for more details.                       *
+# *                                                                         *
+# *   You should have received a copy of the GNU Lesser General Public      *
+# *   License along with FreeCAD. If not, see                               *
+# *   <https://www.gnu.org/licenses/>.                                      *
+# *                                                                         *
+# ***************************************************************************
+# to run the example use:
+"""
+from femexamples.equation_staticcurrent_elmer import setup
+setup()
+
+"""
+
+
+import sys
+import FreeCAD
+
+import Fem
+import ObjectsFem
+
+from BasicShapes import Shapes
+from . import manager
+from .manager import get_meshname
+from .manager import init_doc
+
+
+def get_information():
+    return {
+        "name": "Joule heating",
+        "meshtype": "solid",
+        "meshelement": "Tet10",
+        "constraints": ["electrostatic potential", "current density"],
+        "solvers": ["elmer"],
+        "material": "solid",
+        "equations": ["static current"],
+    }
+
+
+def get_explanation(header=""):
+    return (
+        header
+        + """
+
+To run the example from Python console use:
+from femexamples.equation_staticcurrent_elmer import setup
+setup()
+
+Static current equation - Elmer solver
+
+analytical solution - temperature 351.09 K at 50 s
+
+"""
+    )
+
+
+def setup(doc=None, solvertype="elmer"):
+
+    # init FreeCAD document
+    if doc is None:
+        doc = init_doc()
+
+    # explanation object
+    # just keep the following line and change text string in get_explanation method
+    manager.add_explanation_obj(doc, get_explanation(manager.get_header(get_information())))
+
+    # geometric objects
+
+    # wire
+    Wire = doc.addObject("Part::Cylinder", "Wire")
+    Wire.Radius = "2 mm"
+    Wire.Height = "60 mm"
+    Wire.ViewObject.Visibility = True
+
+    if FreeCAD.GuiUp:
+        Wire.ViewObject.Document.activeView().viewAxonometric()
+        Wire.ViewObject.Document.activeView().fitAll()
+
+    # analysis
+    analysis = ObjectsFem.makeAnalysis(doc, "Analysis")
+    if FreeCAD.GuiUp:
+        import FemGui
+
+        FemGui.setActiveAnalysis(analysis)
+
+    # solver
+    if solvertype == "elmer":
+        solver_obj = ObjectsFem.makeSolverElmer(doc, "SolverElmer")
+        solver_obj.SimulationType = "Transient"
+        solver_obj.TimestepSizes = [50]
+        solver_obj.TimestepIntervals = [1]
+        eq_staticcurrent = ObjectsFem.makeEquationStaticCurrent(doc, solver_obj)
+        eq_staticcurrent.References = [(Wire, "Solid1")]
+        eq_staticcurrent.CalculateJouleHeating = True
+        eq_staticcurrent.HeatSource = True
+        eq_staticcurrent.Priority = 2
+        eq_heat = ObjectsFem.makeEquationHeat(doc, solver_obj)
+        eq_heat.References = [(Wire, "Solid1")]
+        eq_heat.Priority = 1
+    else:
+        FreeCAD.Console.PrintWarning(
+            "Unknown or unsupported solver type: {}. "
+            "No solver object was created.\n".format(solvertype)
+        )
+    analysis.addObject(solver_obj)
+
+    # material
+
+    # metal wire
+    material_obj = ObjectsFem.makeMaterialSolid(doc, "Metal for Joule heating")
+    mat = material_obj.Material
+    mat["Name"] = "Metal for Joule heating"
+    mat["Density"] = "7850 kg/m^3"
+    mat["ThermalConductivity"] = "16.0 W/m/K"
+    mat["SpecificHeat"] = "490.0 J/kg/K"
+    mat["ElectricalConductivity"] = "1450000 S/m"
+    material_obj.Material = mat
+    material_obj.References = [(Wire, "Solid1")]
+    analysis.addObject(material_obj)
+
+    # voltage on one end
+    Voltage = ObjectsFem.makeConstraintElectrostaticPotential(doc, "Voltage")
+    Voltage.References = [(Wire, "Face2")]
+    Voltage.Potential = "0 V"
+    analysis.addObject(Voltage)
+
+    # current on other end
+    Current = ObjectsFem.makeConstraintCurrentDensity(doc, "Current")
+    Current.References = [(Wire, "Face3")]
+    Current.Mode = "Normal"
+    Current.NormalCurrentDensity_re = "2387324 A/m^2"
+    analysis.addObject(Current)
+
+    # constraint initial temperature
+    con_inittemp = ObjectsFem.makeConstraintInitialTemperature(doc, "ConstraintInitialTemperature")
+    con_inittemp.initialTemperature = 300.0
+    analysis.addObject(con_inittemp)
+
+    # mesh
+    femmesh_obj = analysis.addObject(ObjectsFem.makeMeshGmsh(doc, get_meshname()))[0]
+    femmesh_obj.Shape = Wire
+    femmesh_obj.ElementOrder = "2nd"
+    femmesh_obj.CharacteristicLengthMax = "0.7 mm"
+    femmesh_obj.ViewObject.Visibility = False
+
+    # generate the mesh
+    from femmesh import gmshtools
+
+    gmsh_mesh = gmshtools.GmshTools(femmesh_obj, analysis)
+    try:
+        error = gmsh_mesh.create_mesh()
+    except Exception:
+        error = sys.exc_info()[1]
+        FreeCAD.Console.PrintError(f"Unexpected error when creating mesh: {error}\n")
+
+    doc.recompute()
+    return doc