Langley Research Center Turbulence Modeling Resource

Exp: FAITH Hill 3-D Separated Flow

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The data on this page were provided by Kurt Long.

These experimental data are for flow over a 3-dimensional hill, which includes separation. The acronym FAITH stands for "Fundamental Aero Investigates The Hill." The objective of the tests was to characterize both qualitatively and quantitatively a complex 3-D smooth-body separated aerodynamic flow. The data were taken at NASA Ames, as described in the references. Many different testing techniques were employed, including particle image velocimetry (PIV), pressure sensitive paint (PSP), Cobra probe, oil flow, and fringe imaging skin friction (FISF). (The Cobra probe is a probe that measures 3-components of velocity as well as local static pressure in real time.) Documentation for the FAITH Hill experiment can be found in:

• Bell, J. H., Heineck, J. T., Zilliac, G., Mehta, R. D., and Long, K. R., "Surface and Flow Field Measurements on the FAITH Hill Model," AIAA Paper 2012-0704, 2012, https://doi.org/10.2514/6.2012-704.
• Husen, N., Woodiga, S., Liu, T., and Sullivan, J. P., "Global Luminescent Oil-film Skin-Friction Meter Generalized to Three-Dimensional Geometry and Applied to FAITH Hill," AIAA Paper 2014-1237, 2014, https://doi.org/10.2514/6.2014-1237.

Some relevant information is given here, but the interested reader is referred to the above publications and the data files for details:

• Wind tunnel test section: 48 inches wide, 32 inches tall, 120 inches long
• Bump shape in wind tunnel is analytically-defined (h = 3*cos(pi*r/9) + 3, where r is the radial distance from the centroid)
• Bump height h = 6 inches in wind tunnel
• Reynolds number based on hill height = 500,000 in wind tunnel
• Wind tunnel centerline mean velocity = 165 ft/sec
• Ratio of hill height to B.L. thickness in wind tunnel test was approx 3
• Freestream tunnel turbulence intensity level (empty test section) = 0.13%.
• (Note: water channel test section was 16 inches wide x 8 inches deep x 96 inches long, with bump height scaled down to 2 inches; Re was approx 1000)

It should be noted that each set of FAITH tests was conducted over a slightly different range of conditions:

• Cobra: M = 0.141-0.149; freestream temperature range = 52-72 deg F
• PIV: M = 0.143-0.145; freestream temperature range = 48-60 deg F
• PSP: M = 0.134; freestream temperature range = 55-60 deg F
• FISF: M = 0.147; freestream temperature range = 58-61 deg F
• Oil flow: M = 0.143; freestream temperature range = 64-67 deg F

Wind tunnel geometry files can be found here:

• Geometry_files.tar.gz (gzipped tar file, < 1 MB)

FAITH Hill experimental data from the wind tunnel are provided below:

• Cobra data (mean flow velocity data, gzipped tar file, < 1 MB)
  • Warning regarding Cobra data: The cobra probe is a 4 hole pressure probe, and has a cone of acceptance of approx. 40 deg half angle, measured relative to the probe centerline, which itself is aligned with the wind tunnel centerline. The Cobra probe only measures velocities whose direction vector falls within that acceptance cone. The cobra probe thus cannot measure data outside of the 40 deg half angle, such as occurs in reverse flow regions. One should therefore not use the Cobra probe data located in or near the reverse flow regions of this flowfield, since these are outside the probe's capabilities; any such data would be composed only of the very few instantaneous downstream components that happened to fall within the acceptance cone during the sample.
• PIV data (mean flow and turbulence data, gzipped tar file, 4.3 MB) <- updated 05/13/2015
• PSP data (surface pressure data, gzipped tar file, 3.9 MB)
• FISF data (surface skin friction data, gzipped tar file, < 1 MB)

Some presentation files and images can be found here:

• Presentations_and_Pictures.tar.gz (gzipped tar file, 48 MB)

Return to: Data from Experiments - Intro Page

Recent significant updates:
5/13/2015 - updated PIV data files (changed binary .plt files to text .dat files)
12/09/2014 - updated PIV data files (origins made consistent; more details given in its README file)
8/08/2014 - updated the posted information on freestream Mach number and temperature
7/15/2014 - added info on freestream turbulence intensity in empty tunnel
7/01/2014 - added warning regarding use of Cobra probe data in and near separated region

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Last Updated: 07/06/2022