Cfx Sim

Hard constraints

1. CCL is declarative, not imperative: CCL defines WHAT the simulation is, not HOW to run it. Do not write control flow in CCL (use Power Syntax/Perl for that).
2. A .def file is required for solving: .ccl alone cannot be solved — it must be paired with a .def that contains the mesh. Use cfx5cmds -write to inject CCL into a .def.
3. cfx5cmds cannot change mesh topology: Only physics parameters (BCs, solver settings, materials) can be modified via cfx5cmds -write. Geometry/mesh changes require cfx5pre.
4. Post-processing requires .cse session files: cfx5post -batch needs a session file — it cannot accept raw CCL commands. Use Colour Variable (not Variable) for contours.
5. Residual convergence alone does not validate physics: All RMS residuals below target means numerical convergence, but physical correctness requires checking conservation quantities (mass imbalance, forces, monitor points).

Required protocol

Step 0 — Check availability

sim check cfx

Step 1 — Validate inputs (Category A / B / C)

• Category A (must ask user): geometry/mesh (.def file), boundary conditions, materials, turbulence model, acceptance criteria
• Category B (may default): precision (single/double), max iterations, parallel cores
• Category C (derive from files): CCL version, domain names, boundary names

Step 2 — Lint

sim lint <file.ccl>

Step 3 — Execute (one-shot mode)

sim run <file.def> --solver cfx

Step 4 — Interactive post-processing (session mode)

Session mode provides step-by-step feedback after solving:

# Connect with existing results
sim connect --solver cfx   # pass res_file= to load results

# Query boundaries and variables
sim inspect session.boundaries
sim inspect session.variables

# Evaluate quantities with instant feedback
sim exec "evaluate(massFlow()@inlet)"         # → 1.379 [kg s^-1]
sim exec "evaluate(areaAve(Pressure)@outlet)" # → -0.058 [Pa]
sim exec "evaluate(maxVal(Velocity)@Default Domain)"

# Create contour visualization
sim exec "CONTOUR: P\n  Colour Variable = Pressure\n  Location List = Default Domain Default\nEND"

# Export image
sim exec "HARDCOPY:\n  Hardcopy Filename = result.png\n  Hardcopy Format = png\nEND\n>print"

# Disconnect
sim disconnect

Three-phase architecture:

1. cfx5solve -batch — non-interactive solve
2. cfx5post -line — interactive post-processing (CCL + Perl evaluate)
3. Agent sends commands → gets quantitative feedback per step

Step 5 — Verify convergence

Check the .out log or use session queries:

• evaluate(massFlow()@inlet) vs evaluate(massFlow()@outlet) — mass conservation
• All RMS residuals below target in .out file
• Monitor points stabilized

File index