2D NACA 0012 Airfoil: Validation (SST)

Overview

The NACA 0012 is the most extensively measured airfoil section in aerodynamics, and a standard validation benchmark for turbulence models: a smooth, symmetric section whose low-speed lift and drag, and surface pressure distribution, have been documented across many wind-tunnel campaigns. At a moderate incidence the flow stays attached over almost the whole chord, with a strong leading-edge suction peak, a clean, repeatable target for a Reynolds-averaged solver.

This is the $k\text{-}\omega$ SST counterpart of the NACA 0012 validation case: Luminary's SST solution compared directly against experiment, the surface pressure of Gregory & O'Reilly and the lift and drag of Ladson, with the NASA CFL3D and FUN3D reference codes shown alongside. Luminary runs the Menter SST-2003m model; the NASA Turbulence Modeling Resource publishes this case's CFL3D and FUN3D data as the SSTm variant, so the reference series are labeled "SSTm" to name the published variant. Conditions follow the TMR validation page, $M=0.15$, $Re=6\times {10}^6$, $\alpha ={10}^{\circ }$, run on the same 897 × 257 C-grid CFL3D used, so the code-to-code comparison is grid-for-grid.

Problem Setup

The airfoil has unit chord and lies in the x–y plane at an angle of attack of $\alpha ={10}^{\circ }$; lift and drag are recovered by projecting the integrated surface force onto the wind axes. The free stream is air at $M=0.15$ (essentially incompressible) and a chord Reynolds number of $6\times {10}^6$. Turbulence is modeled with $k\text{-}\omega$ SST (SST-2003m); the free-stream turbulence is set to the TMR values (${\mu }_t/{\mu }_{\infty }=0.009$) via direct $k$/$\omega$ inflow, with the far-field point-vortex correction active. Discretization is second-order with no limiter, and every run is driven to a deep residual floor.

The boundary conditions are a no-slip adiabatic wall on the airfoil and a Riemann far field on the outer C-boundary. The mesh is NASA's published Family-I structured C-grid at 897 × 257 points, converted to a quasi-2D unit-span grid; using CFL3D's own grid removes mesh resolution as a variable in the comparison. The experimental data span two facilities and Reynolds numbers (Gregory's pressure data at $Re=2.88\times {10}^6$, Ladson's forces at $Re=6\times {10}^6$); both are shown as reported.

Quantities of Interest

The validation quantities are the surface pressure coefficient $C_p(x/c)$ at $\alpha ={10}^{\circ }$ and the integrated lift and drag coefficients. The pressure distribution is compared to the CFL3D reference and to Gregory's upper-surface measurements; the lift and drag are tabulated beside CFL3D, FUN3D, and Ladson's tripped-boundary-layer measurement, each at $\alpha ={10}^{\circ }$. The upper-surface skin-friction coefficient $C_f(x/c)$ is shown against CFL3D as a supporting boundary-layer check.