VT-NASA CFD Turbulence Model Validation Challenge

A Blind Validation CFD Challenge Case for 3D Smooth-Body Turbulent Flow Separation

CREATe, Center for Research and Engineering in Aero/Hydrodynamic Technologies

Virginia Tech, Blacksburg, VA USA

Overview

Virginia Tech, with support from NASA-Langley, has recently acquired high-quality turbulence model validation data for three-dimensional smooth-body flow separation. The geometry, called the BeVERLI Hill (Benchmark Validation Experiments for RANS and LES Investigations), has been studied at height-based Reynolds numbers of 250k to 650k for subsonic flow. Experimental data have been obtained for the hill at zero and 90 degree orientations and includes extensive oil flow visualizations, surface pressures, skin friction via oil film interferometry, and mean and fluctuating velocities using particle image velocimetry, laser doppler velocimetry, and pitot-static rakes. Extensive boundary conditions and oncoming boundary layer data have also been measured. We propose a blind CFD turbulence modeling challenge case with the BeVERLI Hill oriented at 30 degrees to the oncoming freestream. Two turbulence models are strongly recommended: the standard Spalart-Allmaras model and the Menter k-ω SST model. Additional turbulence model submissions are welcome, as are scale-resolving simulations. While extensive boundary condition information will be made available to participants, the surface pressure, surface skin friction, and velocity data will be withheld until the computations have been submitted, thus making this a blind CFD challenge. A two-dimensional verification case will also be required.

BeVERLI Hill in VT Stability Tunnel with Boundary Conditions

BeVERLI Hill in the 45 Degree Orientation

Currently Available Information

PDF Presentation from AIAA Aviation June 2023 (San Diego)
As-designed and as-built geometry files (Hill only)
Family of systematically-refined structured grids for the as-designed and as-built geometries
Hill height (for use in the Reynolds number): H = 0.186944 m
Inflow boundary conditions, reference pressures, and downstream static pressure: BeVERLI_BCs.pdf
Boundary layer parameters and mean velocity profiles upstream of the Hill: BeVERLI_BCs.pdf
Raw BL velocity profile data, obtained with the Hill installed in the tunnel:

BL rake data at (x₁, x₂, x₃) = (-1.93 m, 0, 0): Re = 250k, Re = 650k
PIV data at (x₁, x₂, x₃) = (-1.83 m, 0, 0): Re = 250k, Re = 650k

Timeline (Updated 4/16/24)

October 2022: wind tunnel entry for surface pressures, oil flow, BCs (completed)
June 2023: AIAA paper and ASME V&V symposium presentation discussing validation challenge
July and October 2023: wind tunnel entries for PTV/PIV, LDV, OFI
October 2023: family of as-built systematically-refined structured grids made available
April 2024: data locations and file formats sent to participants
June 2024: contributors submit data to VT for compilation and analysis
June 24, 2024: AIAA manuscript deadline for those with accepted Aviation abstracts
July 2024: special session at AIAA Aviation (Las Vegas) w/ summary paper, contributor presentations, and exp. data release

Initial VT-NASA CFD Turb. Model Challenge Announcement Flyer (January 2023)

Interested in participating? Please contact Prof. Chris Roy: cjroy@vt.edu

Nominal Boundary Conditions for BeVERLI Hill Simulations

Reynolds Number, Re_H	250,000	650,000
Stagnation Pressure, p_0,in	94,220 Pa	94,450 Pa
Stagnation Temperature, T_0,in	297 K	297 K
Outflow Pressure, p_outflow	93,961 Pa	92,692 Pa
Reference Pressure, p_ref	93,974 Pa	92,771 Pa
Reference Velocity, U_ref	21.11 m/s	55.22 m/s
Reference Mach Number, M_ref	0.06	0.16
Reference Density, ρ_ref	1.103 kg/m³	1.093 kg/m³
Turbulence Intensity, T.I.	0.021%	0.030%
Inflow Viscosity Ratio, (μ_t/μ)_in	1.5	3.0
Inflow TKE, k_in	2.9E-5 m²/s²	4.0E-4 m²/s²
Inflow Spec. Dissipation Rate, ω_in	1.17 1/s	8.12 1/s
Inflow SA Working Variable, ν_in	4.5E-5	9.2E-5

Example Grid Family for the BeVERLI Hill (45 Degree Orientation Shown)

Verification Case: 2D Bump-in-Channel

Turbulence Modeling Resources Page
Run with Spalart-Allmaras one-equation and Menter k-ω SST two-equation models
Results on at least three systematically-refined grids are required
Relative iterative convergence levels must be reported for each governing equation
Grids found here (1409x641 to 89x41 nodes)
Data available here for different turbulence models

Additional Information

Specific data submission file formats will be provided by November 2023
Two hill height-based Reynolds numbers are required: Re_H = 250,000 and 650,000
Results with two turbulence models are strongly recommended: the standard Spalart-Allmaras one-equation model and the Menter k-ω SST two-equation model
Results for other turbulence models are also encouraged, especially nonlinear models (e.g., QCR)
Results with scale-resolving methods are also encouraged
Results on at least three systematically-refined grids are required
Relative iterative convergence levels must be reported for each governing equation