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# Applied: Fine-tune a PMDB export with PMDBExportOptions

PMDB (Persistent Model Database) is the recommended format for transferring
geometry to Ansys Mechanical, Fluent Meshing, DesignModeler, and other Ansys
solvers. By default ``export_to_pmdb()`` exports *everything* — solid bodies,
surface bodies, line bodies, named selections, coordinate systems, planes, and
more.

``PMDBExportOptions`` lets you tailor exactly what ends up in the file. This
is useful when, for example:

- You want to send **only solid bodies** to a structural solver and ignore the
  surface and line bodies that live in the same design.
- You need a **CFD-ready** mesh file that targets Fluent Meshing instead of
  PartMgr.
- You want to strip named selections so that the receiving tool starts with a
  clean slate.

This example builds a simple mixed-body assembly (a solid box and a surface
panel), attaches named selections, and then exports it three ways to
illustrate the most commonly used options.

## Build the assembly

The design contains two body types so that the body-filter options have
something visible to work with:

| Body | Type | Description |
|------|------|-------------|
| `Solid_Box` | Solid | 50 × 30 × 20 mm extruded box |
| `Surface_Panel` | Surface | 60 × 40 mm thin planar panel |

```{code-cell} ipython3
from ansys.geometry.core import launch_modeler
from ansys.geometry.core.math import (
    UNITVECTOR3D_X,
    UNITVECTOR3D_Z,
    Point2D,
    Point3D,
)
from ansys.geometry.core.shapes.box_uv import BoxUV
from ansys.geometry.core.shapes.parameterization import Interval
from ansys.geometry.core.shapes.surfaces import PlaneSurface
from ansys.geometry.core.sketch import Sketch

# ── Launch the Geometry service ────────────────────────────────────────────
modeler = launch_modeler()
design = modeler.create_design("MixedBodyAssembly")
```

### Add a solid body

```{code-cell} ipython3
# Sketch a 50 × 30 mm rectangle and extrude it 20 mm
sketch = Sketch()
sketch.box(Point2D([0, 0]), 0.05, 0.03)  # width=50 mm, height=30 mm (metres)
solid_box = design.extrude_sketch("Solid_Box", sketch, 0.02)  # depth=20 mm
print(f"Solid body created  : '{solid_box.name}'  is_surface={solid_box.is_surface}")
```

### Add a surface (shell) body

Surface bodies — sometimes called *sheet bodies* or *midsurfaces* — have zero
thickness. They are common in thin-walled structural models.

```{code-cell} ipython3
# Build a planar surface offset in Z so it does not overlap the solid box.
# A Plane surface with a BoxUV trim gives a finite rectangular patch.
plane_geom = PlaneSurface(
    origin=Point3D([0, 0, 0.04]),  # 40 mm above the bottom face of the box
    reference=UNITVECTOR3D_X,
    axis=UNITVECTOR3D_Z,
)

# Trim to a 60 × 40 mm rectangle (±0.03 m in X, ±0.02 m in Y)
trimmed = plane_geom.trim(
    BoxUV(range_u=Interval(-0.03, 0.03), range_v=Interval(-0.02, 0.02))
)

surface_panel = design.create_body_from_surface("Surface_Panel", trimmed)
print(f"Surface body created: '{surface_panel.name}'  is_surface={surface_panel.is_surface}")
```

### Visualise the assembly

```{code-cell} ipython3
design.plot()
```

### Create named selections

Named selections are labels that group bodies (or faces/edges/vertices).
They pass through PMDB into Mechanical as *Named Selections*, where they
can scope boundary conditions and mesh controls.

```{code-cell} ipython3
design.create_named_selection("NS_Solid",   bodies=[solid_box])
design.create_named_selection("NS_Surface", bodies=[surface_panel])
design.create_named_selection("NS_All",     bodies=[solid_box, surface_panel])

print("Named selections in design:")
for ns in design.named_selections:
    print(f"  '{ns.name}'")
```

## Export scenarios

The table below summarises the four exports performed in this section.

| Scenario | Key options changed | Purpose |
|----------|---------------------|---------|
| **Default** | *(none)* | Baseline — everything exported |
| **Solids only** | `process_surface_bodies=False` | Strip shells |
| **No named selections** | `named_selection=False` | Clean-slate transfer |
| **CFD target** | `target_application=PMDBTargetApplication.FLUENTMESHING` | Prepare for Fluent Meshing |

```{code-cell} ipython3
from pathlib import Path

from ansys.geometry.core.misc.options import (
    AnalysisType,
    PMDBExportOptions,
    PMDBTargetApplication,
)

output_dir = Path.cwd() / "pmdb_exports"
output_dir.mkdir(exist_ok=True)
```

### Scenario 1 — Default export

No options are passed, so ``export_to_pmdb()`` uses the ``PMDBExportOptions``
defaults, which include all body types and named selections.

```{code-cell} ipython3
path_default = design.export_to_pmdb(output_dir)
print(path_default)
print(f"Default export  → {path_default.name}  ({path_default.stat().st_size:,} bytes)")
```

### Scenario 2 — Solid bodies only

Setting ``process_surface_bodies=False`` tells the exporter to discard
surface bodies. Only the solid box (and its named selection) will be
present in the resulting PMDB file.

```{code-cell} ipython3
opts_solids_only = PMDBExportOptions(
    process_surface_bodies=False,
)

path_solids = design.export_to_pmdb(
    output_dir / "assembly_solids_only.pmdb",
    options=opts_solids_only,
)
print(f"Solids-only export → {path_solids.name}  ({path_solids.stat().st_size:,} bytes)")
```

### Scenario 3 — All body types, but no named selections

Here ``named_selection=False`` strips the named selection data from the
export. This is useful when the downstream tool should not inherit the
groupings defined in CAD.

```{code-cell} ipython3
opts_no_ns = PMDBExportOptions(
    named_selection=False,
)

path_no_ns = design.export_to_pmdb(
    output_dir / "assembly_no_named_selections.pmdb",
    options=opts_no_ns,
)
print(f"No-NS export       → {path_no_ns.name}  ({path_no_ns.stat().st_size:,} bytes)")
```

### Scenario 4 — CFD-ready: target Fluent Meshing

Changing ``target_application`` to ``FLUENTMESHING`` configures the PMDB
for import into Ansys Fluent Meshing.

```{code-cell} ipython3
opts_cfd = PMDBExportOptions(
    target_application=PMDBTargetApplication.FLUENTMESHING,
)

path_cfd = design.export_to_pmdb(
    output_dir / "assembly_fluent_meshing.pmdb",
    options=opts_cfd,
)
print(f"CFD export         → {path_cfd.name}  ({path_cfd.stat().st_size:,} bytes)")
```

## Compare the exported files

A quick size comparison gives a rough indication of how much data each option
set includes.  In a real project the differences in body counts are more
meaningful — here the assembly is intentionally small.

```{code-cell} ipython3
exports = {
    "Default (all bodies + NS)": path_default,
    "Solids only":               path_solids,
    "No named selections":       path_no_ns,
    "CFD / Fluent Meshing":      path_cfd,
}

col_w = max(len(k) for k in exports) + 2
print(f"{'Scenario':<{col_w}} {'File':<45} {'Size (bytes)':>14}")
print("-" * (col_w + 45 + 16))
for label, path in exports.items():
    size = path.stat().st_size
    print(f"{label:<{col_w}} {path.name:<45} {size:>14,}")
```

## Key takeaways

- ``PMDBExportOptions`` is a plain Python dataclass — every field has a
  sensible default, so you only need to override what matters.
- Use ``process_solid_bodies`` and ``process_surface_bodies`` to filter which body types reach the solver.
- Use ``named_selection=False`` if the receiving tool should start without
  pre-defined named selections.
- Use ``target_application`` to tailor the PMDB for a specific Ansys product
  (``PARTMGR``, ``DESIGNMODELER``, ``FLUENTMESHING``, ``AIM``, or
  ``SPACECLAIM``).

## Close the Geometry service

```{code-cell} ipython3
modeler.close()
```

### References

- [PMDBExportOptions API reference](https://geometry.docs.pyansys.com/version/stable/api/ansys/geometry/core/misc/options/PMDBExportOptions.html)
- [Design.export_to_pmdb API reference](https://geometry.docs.pyansys.com/version/stable/api/ansys/geometry/core/designer/design/Design.html#Design.export_to_pmdb)
- [PyAnsys Geometry examples gallery](https://geometry.docs.pyansys.com/version/stable/examples/index.html)