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Magnetic behavior of a magnet-collector system

This example shows how to use PyAEDT to understand the magnetic behavior of a simplified magnet-collector system when the magnet position changes. The example shows how to setup the model, an optimetrics analysis to sweep the magnet position and the post-processing of the results, from report creation to field plotting using PyVista.

Keywords: Maxwell 3D, Magnetostatic, Magnetic, Optimetrics.

Perform imports and define constants

Perform required imports.

import os
import tempfile
import time

import ansys.aedt.core  # Interface to Ansys Electronics Desktop
from ansys.aedt.core.generic.constants import Axis

Define constants

Constants help ensure consistency and avoid repetition throughout the example.

AEDT_VERSION = "2025.2"
NUM_CORES = 4
NG_MODE = False  # Open AEDT UI when it is launched.

Create temporary directory

Create a temporary working directory. The name of the working folder is stored in temp_folder.name.

Note: The final cell in the notebook cleans up the temporary folder. If you want to retrieve the AEDT project and data, do so before executing the final cell in the notebook.

temp_folder = tempfile.TemporaryDirectory(suffix=".ansys")

Launch Maxwell 3d

Create an instance of the Maxwell3d class. The Ansys Electronics Desktop will be launched with an active Maxwell3D design. The m3d object is subsequently used to create and simulate the model.

m3d = ansys.aedt.core.Maxwell3d(
    project="magnet_collector",
    solution_type="Magnetostatic",
    version=AEDT_VERSION,
    non_graphical=NG_MODE,
    new_desktop=True,
)

PyAEDT INFO: Python version 3.10.11 (tags/v3.10.11:7d4cc5a, Apr  5 2023, 00:38:17) [MSC v.1929 64 bit (AMD64)].
PyAEDT INFO: PyAEDT version 0.22.dev0.
PyAEDT INFO: Initializing new Desktop session.
PyAEDT INFO: Log on console is enabled.
PyAEDT INFO: Log on file C:\Users\ansys\AppData\Local\Temp\pyaedt_ansys_4725f2f7-a117-4c0a-8789-45d7c8ffce92.log is enabled.
PyAEDT INFO: Log on AEDT is disabled.
PyAEDT INFO: Debug logger is disabled. PyAEDT methods will not be logged.
PyAEDT INFO: Launching PyAEDT with gRPC plugin.
PyAEDT INFO: New AEDT session is starting on gRPC port 59559.
PyAEDT INFO: Electronics Desktop started on gRPC port: 59559 after 10.635896921157837 seconds.
PyAEDT INFO: AEDT installation Path C:\Program Files\ANSYS Inc\v252\AnsysEM
PyAEDT INFO: Ansoft.ElectronicsDesktop.2025.2 version started with process ID 2552.
PyAEDT INFO: Project magnet_collector has been created.
PyAEDT INFO: No design is present. Inserting a new design.
PyAEDT INFO: Added design 'Maxwell 3D_X7H' of type Maxwell 3D.
PyAEDT INFO: Aedt Objects correctly read

Define variables

Later on we want to see how the magnetic behavior of the system changes with the position of the magnet.

m3d["magnet_radius"] = "2mm"
m3d["magnet_height"] = "15mm"
m3d["magnet_z_pos"] = "0mm"

Add materials

Create custom material "Aimant".

mat = m3d.materials.add_material("Aimant")
mat.permeability = "1.1"
mat.set_magnetic_coercivity(value=2005600, x=1, y=1, z=0)
mat.update()

PyAEDT INFO: Materials class has been initialized! Elapsed time: 0m 0sec
PyAEDT INFO: Adding new material to the Project Library: Aimant
PyAEDT INFO: Material has been added in Desktop.

True

Create non-linear magnetic material with single valued BH curve

Create list with BH curve data

bh_curve = [
    [0.0, 0.0],
    [0.032, 0.5],
    [0.049, 0.8],
    [0.065, 1],
    [0.081, 1.13],
    [0.17, 1.52],
    [0.32, 1.59],
    [0.65, 1.62],
    [0.81, 1.65],
    [1.61, 1.7],
    [3.19, 1.75],
    [4.78, 1.79],
    [6.34, 1.83],
    [7.96, 1.86],
    [15.89, 1.99],
    [31.77, 2.1],
    [63.53, 2.2],
    [158.77, 2.41],
    [317.48, 2.65],
    [635, 3.1],
]

Create custom material “Fer” and assign the BH curve to the permeability value

mat = m3d.materials.add_material("Fer")
mat.permeability.value = bh_curve
mat.set_magnetic_coercivity(value=0, x=1, y=0, z=0)
mat.update()

PyAEDT INFO: Adding new material to the Project Library: Fer
PyAEDT INFO: Material has been added in Desktop.

True

Create the collector

Create a simple geometry to model the collector and assign a material to it.

collector = m3d.modeler.create_cylinder(
    orientation=ansys.aedt.core.constants.Axis.Z,
    origin=[12, 13, 25],
    height="3mm",
    radius="9.5mm",
    axisdir="Z",
    name="collector",
)
cylinder2 = m3d.modeler.create_cylinder(
    orientation=ansys.aedt.core.constants.Axis.Z,
    origin=[12, 13, 25],
    height="3mm",
    radius="8mm",
    axisdir="Z",
    name="cyl2",
)

m3d.modeler.subtract(
    blank_list=[collector], tool_list=[cylinder2], keep_originals=False
)

cylinder3 = m3d.modeler.create_cylinder(
    orientation=ansys.aedt.core.constants.Axis.Z,
    origin=[12, 13, 28],
    height="3mm",
    radius="8.7mm",
    axisdir="Z",
    name="cyl3",
)
cylinder4 = m3d.modeler.create_cylinder(
    orientation=ansys.aedt.core.constants.Axis.Z,
    origin=[12, 13, 28],
    height="3mm",
    radius="2mm",
    axisdir="Z",
    name="cyl4",
)

m3d.modeler.subtract(
    blank_list=[cylinder3], tool_list=[cylinder4], keep_originals=False
)
m3d.modeler.unite(assignment=[collector, cylinder3], keep_originals=False)

collector.material_name = "Fer"

PyAEDT INFO: Modeler class has been initialized! Elapsed time: 0m 1sec
PyAEDT INFO: Parsing design objects. This operation can take time
PyAEDT INFO: Refreshing bodies from Object Info
PyAEDT INFO: Bodies Info Refreshed Elapsed time: 0m 0sec
PyAEDT INFO: 3D Modeler objects parsed. Elapsed time: 0m 0sec
PyAEDT INFO: Parsing design objects. This operation can take time
PyAEDT INFO: Refreshing bodies from Object Info
PyAEDT INFO: Bodies Info Refreshed Elapsed time: 0m 0sec
PyAEDT INFO: 3D Modeler objects parsed. Elapsed time: 0m 0sec
PyAEDT INFO: Parsing design objects. This operation can take time
PyAEDT INFO: Refreshing bodies from Object Info
PyAEDT INFO: Bodies Info Refreshed Elapsed time: 0m 0sec
PyAEDT INFO: 3D Modeler objects parsed. Elapsed time: 0m 0sec
PyAEDT INFO: Union of 2 objects has been executed.

Create magnet

Create a cylinder and assign a material to it.

magnet = m3d.modeler.create_cylinder(
    orientation=Axis.Z,
    origin=[0, 0, "magnet_z_pos"],
    radius="magnet_radius",
    height="magnet_height",
    num_sides=0,
    name="magnet",
    material="Aimant",
)

Create a polyline

Create a polyline to plot the field onto. The polyline is placed in the center of the collector so to capture the magnetic flux density.

line = m3d.modeler.create_polyline(points=[[12, 13, 0], [12, 13, "32mm"]], name="line")

Create a vacuum region to enclose all objects

region = m3d.modeler.create_region(
    pad_value=50, pad_type="Percentage Offset", name="Region"
)

Create the collector cross-section on the XZ plane

collector_relative_cs = m3d.modeler.create_coordinate_system(
    origin=[12, 13, 28], name="collector_cs"
)
section = m3d.modeler.create_rectangle(
    orientation="XZ",
    origin=[-25, 0, -35],
    sizes=["50mm", "50mm"],
    name="section",
)
m3d.modeler.set_working_coordinate_system("Global")

True

Create a dummy geometry for mesh operations

Create a cylinder that encloses the polyline to force the mesh to be finer on the polyline.

dummy_cylinder = m3d.modeler.create_cylinder(
    orientation=Axis.Z,
    origin=[12, 13, 0],
    radius="1mm",
    height="32mm",
    num_sides=6,
    name="dummy_cylinder",
)

Create a custom named expression

Create a custom named expression to calculate relative permeability of the ferromagnetic material. This expression is used to see how the relative permeability of the collector changes with magnet position.

mu_r = {
    "name": "mu_r",
    "description": "Relative permeability of the ferromagnetic material",
    "design_type": ["Maxwell 3D"],
    "fields_type": ["Fields"],
    "primary_sweep": "Time",
    "assignment": "",
    "assignment_type": [""],
    "operations": [
        "NameOfExpression('Mag_B')",
        "NameOfExpression('Mag_H')",
        "Scalar_Constant(1.25664e-06)",
        "Operation('*')",
        "Operation('/')",
    ],
    "report": ["Field_3D"],
}
m3d.post.fields_calculator.add_expression(mu_r, None)

PyAEDT INFO: Parsing C:\Users\ansys\Documents\Ansoft\magnet_collector.aedt.
PyAEDT INFO: File C:\Users\ansys\Documents\Ansoft\magnet_collector.aedt correctly loaded. Elapsed time: 0m 0sec
PyAEDT INFO: aedt file load time 0.015939950942993164
PyAEDT INFO: PostProcessor class has been initialized! Elapsed time: 0m 0sec
PyAEDT INFO: PostProcessor class has been initialized! Elapsed time: 0m 0sec
PyAEDT INFO: Post class has been initialized! Elapsed time: 0m 0sec

'mu_r'

Set mesh operations

Assign mesh operations to the dummy cylinder and the collector.

poly_mesh = m3d.mesh.assign_length_mesh(
    assignment=[dummy_cylinder], maximum_length="1mm", name="polyline"
)
collector_mesh = m3d.mesh.assign_length_mesh(
    assignment=[collector],
    inside_selection=False,
    maximum_length="3.8mm",
    name="collector",
)

PyAEDT INFO: Mesh class has been initialized! Elapsed time: 0m 0sec
PyAEDT INFO: Mesh class has been initialized! Elapsed time: 0m 0sec

Create simulation setup

setup = m3d.create_setup()
setup.props["MaximumPasses"] = 10
setup.props["PercentRefinement"] = 30
setup.props["PercentError"] = 2
setup.props["MinimumPasses"] = 2
setup.props["NonlinearResidual"] = 1e-3

Add parametric sweep

Create a linear count sweep where the parameter to sweep is "magnet_z_pos". The magnet position is changed at each step to see how the magnetic behavior of the system changes. Enable the saving fields option.

param_sweep = m3d.parametrics.add(
    variable="magnet_z_pos",
    start_point=m3d["magnet_z_pos"],
    end_point="25mm",
    step=5,
    variation_type="LinearCount",
)

param_sweep.props["ProdOptiSetupDataV2"]["SaveFields"] = True

Analyze parametric sweep

param_sweep.analyze(cores=NUM_CORES)

PyAEDT INFO: Project magnet_collector Saved correctly
PyAEDT INFO: Key Desktop/ActiveDSOConfigurations/Maxwell 3D correctly changed.
PyAEDT INFO: Solving Optimetrics
PyAEDT INFO: Design setup Parametric_HID1CN solved correctly in 0.0h 1.0m 41.0s
PyAEDT INFO: Key Desktop/ActiveDSOConfigurations/Maxwell 3D correctly changed.

True

Create reports

Create rectangular and data plots on the polyline for different magnet positions.

data_table = m3d.post.create_report(
    expressions="Mag_B",
    report_category="Fields",
    plot_type="Data Table",
    plot_name="Mag_B",
    variations={"magnet_z_pos": "All"},
    context=line.name,
    polyline_points=101,
)

rectangular_plot = m3d.post.create_report(
    expressions="Mag_B",
    report_category="Fields",
    plot_type="Rectangular Plot",
    plot_name="Mag_B",
    variations={"magnet_z_pos": "All"},
    context=line.name,
    polyline_points=101,
)

Create field plots

Create field plots over the collector cross-section and on the collector surface to see how the magnetic flux density (B), the vector B field, the magnetic field strength (H) and the permeability of the ferromagnetic material (μ) change.

mag_b = m3d.post.create_fieldplot_surface(
    assignment=[section.name], quantity="Mag_B", plot_name="Mag_B", field_type="Fields"
)
vector_b = m3d.post.create_fieldplot_volume(
    assignment=[collector.name],
    quantity="B_Vector",
    plot_name="B_Vector",
    field_type="Fields",
)
mag_h = m3d.post.create_fieldplot_surface(
    assignment=[section.name], quantity="Mag_H", plot_name="Mag_H", field_type="Fields"
)
mu_r = m3d.post.create_fieldplot_surface(
    assignment=[collector.name], quantity="mu_r", plot_name="mu_r", field_type="Fields"
)

PyAEDT INFO: Active Design set to Maxwell 3D_X7H
PyAEDT INFO: Active Design set to Maxwell 3D_X7H
PyAEDT INFO: Active Design set to Maxwell 3D_X7H
PyAEDT INFO: Active Design set to Maxwell 3D_X7H

Export field

Export magnetic flux density B on the collector cross-section in a .fld file.

fld_filename = os.path.join(temp_folder.name, "Mag_B.fld")
m3d.post.export_field_file(
    quantity="Mag_B",
    output_file=fld_filename,
    assignment=section.name,
    objects_type="Surf",
)

PyAEDT INFO: Exporting 'Mag_B' field. Please be patient.

WindowsPath('C:/Users/ansys/AppData/Local/Temp/tmp6qz1461k.ansys/Mag_B.fld')

Overlay fields using PyVista

Plot electric field using PyVista and save to an image file. Plot the relative permeability on the collector surface at a given magnet position. Change argument "show" to True see the permeability plot.

m3d["magnet_z_pos"] = "18.75mm"

py_vista_plot = m3d.post.plot_field(
    quantity="mu_r", assignment=collector.name, plot_cad_objs=True, show=False
)
py_vista_plot.isometric_view = True
py_vista_plot.plot(
    export_image_path=os.path.join(temp_folder.name, "mu_r.jpg"), show=True
)

PyAEDT INFO: Active Design set to Maxwell 3D_X7H

ERROR:root:Cell array MaterialIds with 1 components, has only 0 tuples but there are 1 cells
ERROR:root:Cell array MaterialIds with 1 components, has only 0 tuples but there are 1 cells
ERROR:root:Cell array MaterialIds with 1 components, has only 0 tuples but there are 1 cells
ERROR:root:Cell array MaterialIds with 1 components, has only 0 tuples but there are 1 cells
ERROR:root:Cell array MaterialIds with 1 components, has only 0 tuples but there are 1 cells
ERROR:root:Cell array MaterialIds with 1 components, has only 0 tuples but there are 1 cells
ERROR:root:Cell array MaterialIds with 1 components, has only 0 tuples but there are 1 cells

True

BH curve of the ferromagnetic material

From the plot exported in the previous section, we can see the trend of the relative permeability when the magnet gets close to the collector. Looking at the scale of the relative permeability, we can see that the collector is far from saturation. With a permeability peak value around 1.3E+7, the collector is still in the linear region of the BH curve.

Release AEDT

m3d.save_project()
m3d.release_desktop()
# Wait 3 seconds to allow AEDT to shut down before cleaning the temporary directory.
time.sleep(3)

PyAEDT INFO: Project magnet_collector Saved correctly

INFO:Global:Project magnet_collector Saved correctly

PyAEDT INFO: Desktop has been released and closed.

INFO:Global:Desktop has been released and closed.

Clean up

All project files are saved in the folder temp_folder.name. If you’ve run this example as a Jupyter notebook, you can retrieve those project files. The following cell removes all temporary files, including the project folder.

temp_folder.cleanup()

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