xfoil-analysislisted

# XFOIL Airfoil Polar Analysis (aerodynamics/airfoil/xfoil-analysis) Use when the task is airfoil section analysis with XFOIL-style tools: polar run planning, polar-point plausibility checks, and validation against classic airfoil data. ## Domain quick reference - XFOIL is a panel-method airfoil analysis tool: inviscid (potential-flow) mode plus an integral boundary-layer coupling for viscous analysis with free or forced transition. - Reynolds number scales the viscous solution; typical validation runs use Re = 6e6. - Classic anchor (NACA Report 824, brief 05 item 7): NACA 0012 at Re = 6e6 gives cl about 0.82 at 10 degrees angle of attack and zero-lift drag coefficient cd0 about 0.0079. - Inviscid XFOIL runs return drag values that are not meaningful; drag requires the viscous analysis. - Polar plausibility bands: alpha in [-25, 30] degrees, cl in [-2.5, 2.5], cd in [0, 0.2]. ## Workflow 1. Set the airfoil coordinates, Reynolds number, and Mach number for the polar. 2. Plan viscous runs (with transition) for drag; treat inviscid runs as lift-only scouting. 3. Run the polar and validate each point structurally with scripts/xfoil_analysis_logic.py. 4. Check NACA 0012 at Re = 6e6 results against the anchor bands (cl at 10 deg 0.77-0.87, cd0 0.0069-0.0089). 5. Use the drag hints (inviscid-run or high-drag) to decide on reruns with transition and finer mesh. ## Pitfalls - Quoting inviscid drag as a real result. - cd0 near zero reported without r