NASA CRM: AIAA Drag Prediction Workshop 6

Overview

The NASA Common Research Model (CRM) is a transonic transport configuration that serves as the reference geometry for the AIAA CFD Drag Prediction Workshop series. The workshops compare computed forces and surface pressures against wind-tunnel measurements across many independent solvers. The sixth workshop (DPW-6, 2016) addressed the CRM Wing-Body at its transonic cruise design point.

This is a flagship validation benchmark. Luminary entered the workshop case, and the results reproduced here are taken from that published case study. Two turbulence models, the Spalart–Allmaras Standard model and Menter's $k\text{-}\omega$ SST-2003m model, are run at the same conditions, and the surface pressure distributions are compared against the NASA wind-tunnel data. The figures and force coefficients on this page are taken from the published case study; they are not recomputed in this repository.

Problem Setup

The geometry is the CRM Wing-Body. The flow is compressible (ideal-gas air) at a free-stream Mach number of $M_{\infty }=0.85$ and a chord Reynolds number of $Re=5\times {10}^6$; the incidence is trimmed so that the lift coefficient is held at the workshop design value $C_L=0.5$. No-slip adiabatic walls are imposed on the aircraft surfaces and a Riemann far field on the outer boundary.

The mesh has roughly 71 million control volumes, with the first cell off the wall sized so that $y^{+}\approx 1$ over the wing and fuselage surfaces (a low-Reynolds-number wall-resolved mesh without wall functions). The two turbulence models, the Spalart–Allmaras Standard model and Menter's $k\text{-}\omega$ SST-2003m model, are run at these same conditions.

Quantities of Interest

The validation quantities are the surface pressure coefficient $C_p(x/c)$ at three spanwise stations and the integrated force coefficients at the fixed $C_L=0.5$: the total drag $C_D$ and its pressure-drag component $C_{D_p}$.

The pressure distributions are reported at three semi-span stations, $\eta =0.95$, $0.73$ and $0.13$ (95%, 72.68% and 13.1% of the semi-span), shown left to right. At each station the distributions from both turbulence models are overlaid on the NASA wind-tunnel measurements, so the chordwise loading on the upper and lower surfaces can be read directly across the span.

For the Spalart–Allmaras Standard model at $C_L=0.5$, the integrated total drag is $C_D=0.0258$ and the pressure-drag component is $C_{D_p}=0.0143$. The range reported by the DPW-6 participants is $C_D=0.0254\text{–}0.0263$ and $C_{D_p}=0.0140\text{–}0.0152$.