Download this example

Download this example as a Jupyter Notebook or as a Python script.

---

Fields export in transient analysis

This example shows how to leverage PyAEDT to set up a Maxwell 3D transient analysis and then compute the average value of the current density field over a specific coil surface and the magnitude of the current density field over all coil surfaces at each time step of the transient analysis.

Keywords: Maxwell 3D, transient, fields calculator, field export.

Perform imports and define constant

Perform required imports.

import tempfile
import time

import ansys.aedt.core
from ansys.aedt.core.examples.downloads import download_file
from ansys.aedt.core.generic.constants import unit_converter

Define constants.

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

Create temporary directory

Create a temporary directory where downloaded data or dumped data can be stored. If you’d like to retrieve the project data for subsequent use, the temporary folder name is given by temp_folder.name

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

Import project

The files required to run this example are downloaded into the temporary working folder.

project_path = download_file(
    source="maxwell_transient_fields",
    name="M3D_Transient_StrandedWindings.aedt",
    local_path=temp_folder.name,
)

Initialize and launch Maxwell 3D

Initialize and launch Maxwell 3D, providing the version and the path of the project.

m3d = ansys.aedt.core.Maxwell3d(
    project=project_path, version=AEDT_VERSION, non_graphical=NG_MODE
)

Create setup and validate

Create the setup specifying general settings such as StopTime, TimeStep, and SaveFieldsType.

setup = m3d.create_setup(name="Setup1")
setup.props["StopTime"] = "0.02s"
setup.props["TimeStep"] = "0.002s"
setup.props["SaveFieldsType"] = "Every N Steps"
setup.props["N Steps"] = "2"
setup.props["Steps From"] = "0s"
setup.props["Steps To"] = "0.02s"
setup.update()

Create field expressions

Create a field expression to evaluate the J field normal to a surface using the advanced fields calculator. The expression is created as a dictionary and then provided as an argument to the add_expression() method.

j_normal = {
    "name": "Jn",
    "description": "J field normal to a surface",
    "design_type": ["Maxwell 3D"],
    "fields_type": ["Fields"],
    "primary_sweep": "Time",
    "assignment": "",
    "assignment_type": [""],
    "operations": [
        "NameOfExpression('<Jx,Jy,Jz>')",
        "Operation('Normal')",
        "Operation('Dot')",
    ],
    "report": ["Field_3D"],
}
m3d.post.fields_calculator.add_expression(j_normal, None)

Calculate the average value of the J field normal using the advanced fields calculator.

j_avg = {
    "name": "Jn_avg",
    "description": "Average J field normal to a surface",
    "design_type": ["Maxwell 3D"],
    "fields_type": ["Fields"],
    "primary_sweep": "Time",
    "assignment": "Coil_A2_ObjectFromFace1",
    "assignment_type": [""],
    "operations": [
        "NameOfExpression('Jn')",
        "EnterSurface('assignment')",
        "Operation('SurfaceValue')",
        "Operation('Mean')",
    ],
    "report": ["Field_3D"],
}
m3d.post.fields_calculator.add_expression(j_avg, None)

Analyze setup specifying setup name

m3d.analyze_setup(name=setup.name, cores=NUM_CORES)

Get available report quantities

Get the available report quantities given a specific report category. In this case, Calculator Expressions is the category.

report_types = m3d.post.available_report_types
quantity = m3d.post.available_report_quantities(
    report_category="Fields", quantities_category="Calculator Expressions"
)

Compute time steps of the analysis

Create a fields report object given the nominal sweep. Get the report solution data to compute the time steps of the transient analysis.

sol = m3d.post.reports_by_category.fields(setup=m3d.nominal_sweep)
data = sol.get_solution_data()
time_steps = data.intrinsics["Time"]

Create field plots over the coil surfaces and export field data

Convert each time step into millimeters. Create field plots over the surface of each coil by specifying the coil object, the quantity to plot, and the time step.

The average value of the J field normal is plotted on the Coil_A2 surface for every time step. The J field is plotted on the surface of each coil for every time-step. Fields data is exported to the temporary folder as an AEDTPLT file.

unit = data.units_sweeps["Time"]
converted = unit_converter(time_steps, "Time", unit, "ms")
for time_step in converted:
    m3d.post.create_fieldplot_surface(
        assignment=m3d.modeler.objects_by_name["Coil_A2"],
        quantity=quantity[0],
        plot_name="J_{}_ms".format(time_step),
        intrinsics={"Time": "ms"},
    )
    mean_j_field_export = m3d.post.export_field_plot(
        plot_name="J_{}_ms".format(time_step),
        output_dir=temp_folder.name,
        file_format="aedtplt",
    )
    m3d.post.create_fieldplot_surface(
        assignment=[
            o for o in m3d.modeler.solid_objects if o.material_name == "copper"
        ],
        quantity="Mag_J",
        plot_name="Mag_J_Coils_{}_ms".format(time_step),
        intrinsics={"Time": "ms"},
    )
    mag_j_field_export = m3d.post.export_field_plot(
        plot_name="Mag_J_Coils_{}_ms".format(time_step),
        output_dir=temp_folder.name,
        file_format="aedtplt",
    )

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)

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()

---

Download this example

Download this example as a Jupyter Notebook or as a Python script.