Legacy meshing interface

The legacy PyFluent meshing interface for the API-based meshing infrastructure is distinct from the classic meshing workflow (Classic meshing workflow).

Supported versions

• Available in PyFluent with Ansys Fluent versions prior to 2026 R1.

• Also supported when using PyFluent with Ansys Fluent 2026 R1 or later version.

Enable the legacy interface

Pass legacy=True during the workflow initialization:

watertight = meshing_session.watertight(legacy=True)
fault_tolerant = meshing_session.fault_tolerant(legacy=True)

Portability

You can pass legacy=True unconditionally to avoid version checks and keep earlier scripts working unchanged.

Fault-tolerant meshing workflow

In the legacy fault-tolerant workflow, PartManagement and PMFileManagement are accessed directly from the meshing session. Use these objects and their methods as shown below:

- meshing_session.PartManagement.InputFileChanged(...)
- meshing_session.PMFileManagement.FileManager.LoadFiles()
- meshing_session.PartManagement.Node["Meshing Model"].Copy(...)
- meshing_session.PartManagement.ObjectSetting["DefaultObjectSetting"].OneZonePer.set_state(...)

Note

Backward compatible: These entries are still supported in PyFluent using Ansys Fluent 2026 R1 for legacy scripts.

Import CAD and part management

import ansys.fluent.core as pyfluent
from ansys.fluent.core import examples

import_file_name = examples.download_file(
    "exhaust_system.fmd", "pyfluent/exhaust_system"
)
meshing_session = pyfluent.launch_fluent(precision=pyfluent.Precision.DOUBLE, processor_count=2, mode=pyfluent.FluentMode.MESHING)

fault_tolerant = meshing_session.fault_tolerant(legacy=True)
meshing_session.PartManagement.InputFileChanged(
    FilePath=import_file_name, IgnoreSolidNames=False, PartPerBody=False
)
meshing_session.PMFileManagement.FileManager.LoadFiles()
meshing_session.PartManagement.Node["Meshing Model"].Copy(
    Paths=[
        "/dirty_manifold-for-wrapper," + "1/dirty_manifold-for-wrapper,1/main,1",
        "/dirty_manifold-for-wrapper," + "1/dirty_manifold-for-wrapper,1/flow-pipe,1",
        "/dirty_manifold-for-wrapper," + "1/dirty_manifold-for-wrapper,1/outpipe3,1",
        "/dirty_manifold-for-wrapper," + "1/dirty_manifold-for-wrapper,1/object2,1",
        "/dirty_manifold-for-wrapper," + "1/dirty_manifold-for-wrapper,1/object1,1",
    ]
)
meshing_session.PartManagement.ObjectSetting["DefaultObjectSetting"].OneZonePer.set_state("part")

import_cad = fault_tolerant.import_cad_and_part_management
import_cad.context.set_state(0)
import_cad.create_object_per.set_state("Custom")
import_cad.fmd_file_name.set_state(import_file_name)
import_cad.file_loaded.set_state("yes")
import_cad.object_setting.set_state("DefaultObjectSetting")
import_cad()

Renaming tasks in workflow

In the legacy workflow, renaming a task updates its Python attribute path. Access the task by the new name.

Note

Not backward compatible: In the enhanced workflow (Ansys Fluent 2026 R1 and later), changing a task’s display name does not change its Python attribute path.

watertight.import_geometry.rename(new_name="import_geom_wtm")
assert watertight.import_geom_wtm

Deleting tasks from workflow

In the legacy workflow, you delete tasks by passing their Python attribute names as strings in list_of_tasks.

Note

Partly backward compatible: In the enhanced workflow (Ansys Fluent 2026 R1 and later), delete-by-name has been replaced by passing task objects to list_of_tasks. Calling task.delete() on a task object still works.

watertight.delete_tasks(list_of_tasks=["create_volume_mesh_wtm", "add_boundary_layers"])
watertight.update_regions.delete()