fluent-sim git:20260511.73fbe2eA

Immutable. This exact content never changes and is served at /api/v1/blob/fc47226d2fedd8e0.

---
name: fluent-sim
description: Use when working with Ansys Fluent through live sim sessions, direct PyFluent scripts, or file-side artifact review.
---

# fluent-sim

This skill is the Fluent-specific operating guide. Choose the control path
that fits the task, then load only the references needed for that path.

## Choose The Control Path

| Path | Best for | Starting point |
|---|---|---|
| Live sim session | Stateful edits, GUI observation, incremental solver work, remote Windows diagnostics, version probes, and inspecting a running Fluent session | `uv run sim connect --solver fluent --mode <solver|meshing> --ui-mode <gui|no_gui>` |
| Direct PyFluent script | Deterministic batch runs, reproducible examples, CI-friendly smoke scripts, and workflows that can own their process lifecycle | `from ansys.fluent.core import launch_fluent` in a normal Python script |
| File-side artifact review | Case/data/mesh inventory, transcript tails, CSV/PNG/PDF outputs, and offline checks that do not need a live solver | Use Python file readers, text inspection, and Fluent artifact helpers before opening a session |

Use sim when the task needs a persistent runtime or live observation. Use a
direct PyFluent script when a one-shot batch program is clearer. Use file-side
helpers when the question is about artifacts already on disk.

## Live Sim Session

After connecting, inspect:

```bash
uv run sim inspect session.versions
uv run sim inspect session.health
uv run sim inspect session.summary
```

The `session.versions` payload selects the active overlays. Always read
`base/`, then the active `sdk/<active_sdk_layer>/`, then the active
`solver/<active_solver_layer>/` when present. Later layers override earlier
files with the same name.

Expected SDK layer directories are:

- `sdk/0.38/` for PyFluent 0.38.x
- `sdk/0.37/` for PyFluent 0.37.x

Useful live inspect targets:

- `session.summary`
- `session.health`
- `session.versions`
- `last.result`
- `workflow.summary`
- `field.catalog` / `fluent.field.catalog`
- `fluent.models.summary`
- `fluent.boundaries.summary`
- `fluent.case.summary`
- `fluent.mesh.summary`
- `fluent.files`

Use `uv run sim exec` snippets with the injected `session`, `solver`, or `meshing`
object. Keep snippets small enough that `last.result` can prove the current
state before the next step.

## Direct PyFluent Script

For direct scripts, own the launch and teardown explicitly:

```python
from ansys.fluent.core import launch_fluent

solver = launch_fluent(mode="solver", ui_mode="no_gui", precision="double")
try:
    solver.settings.file.read_case(file_name="case.cas.h5")
    solver.solution.initialization.hybrid_initialize()
    solver.solution.run_calculation.iterate(iter_count=10)
finally:
    solver.exit()
```

This path is a good fit when the result can be produced in one deterministic
program and you do not need a live agent-visible session between steps.

For direct PyFluent scripts, launch the session normally with PyFluent and do
not rely on sim-injected variables.

## File-Side Artifact Review

Before launching Fluent, inventory what is already present:

- `.cas` / `.cas.h5`: case setup
- `.dat` / `.dat.h5`: solution data
- `.msh` / `.msh.h5`: mesh input
- `.trn` / `.jou`: transcript and journal evidence
- `.pdf` / `.fla`: flamelet and PDF table artifacts
- `.csv` / `.png` / `.json`: exported reports, figures, and structured output

Use this path for quick triage, output extraction, and deciding whether a live
session is necessary.

## Layered References

| Path | Use |
|---|---|
| `base/reference/task_templates.md` | Required inputs and workflow step order |
| `base/reference/runtime_patterns.md` | Fluent dependency chains and state ordering |
| `base/reference/acceptance_checklists.md` | Completion checks for bundled workflows |
| `base/reference/api_discovery.md` | `dir()` and `child_names` patterns for renamed APIs |
| `base/reference/tui_vs_settings.md` | When to prefer Settings API or TUI |
| `base/reference/pyfluent_overview.md` | Quick PyFluent orientation |
| `base/snippets/` | Reusable live-session snippets |
| `base/workflows/` | Longer workflow examples |
| `sdk/0.38/` | PyFluent 0.38.x docs and examples |
| `sdk/0.37/` | PyFluent 0.37.x compatibility notes |
| `solver/25.2/` | Fluent 25.2-specific notes |
| `doc-search/` | Local Fluent documentation search helper |

For PyFluent API questions, start with the active `sdk/` overlay. For Fluent
physics, meshing, UDF, or solver-model questions, use `doc-search/` against the
local Ansys documentation tree rather than guessing names or defaults.

## Live Sim Session Constraints

These constraints apply only after sim has already created a live Fluent
session:

1. Do not call `pyfluent.launch_fluent()` inside a `uv run sim exec` snippet. Use the
   injected `session`, `solver`, or `meshing` object.
2. Do not switch between meshing and solver mode by assumption. The mode is
   selected at connect time unless a Fluent workflow explicitly returns a
   solver object.
3. Confirm each stateful step before sending the next dependent step. Fluent
   meshing and solver workflows are order-sensitive.
4. Use GUI actuation only for surfaces the SDK cannot reach. Prefer
   `solver.settings.*`, `session.tui.*`, and `meshing.workflow.*` for
   reproducible work.

## Flamelet And PDF Table Workflows

For partially premixed steady-diffusion flamelet workflows, load:

- `base/reference/task_templates.md` - Template 5
- `base/reference/runtime_patterns.md` - staged flamelet/PDF dependency chain
- `base/reference/acceptance_checklists.md` - Checklist 5
- `base/snippets/setup_partially_premixed_flamelet.py`
- `base/snippets/write_pdf_table.py`
- `base/snippets/read_case_pdf_data.py`
- `base/snippets/inspect_reacting_bc_scalars.py`

Short version: import CHEMKIN as `flamelet-mixture`, generate flamelets and the
PDF table, persist the table with `write_pdf_cmd(...)`, and restart or
postprocess with `read_case -> read_pdf -> read_data`.