Approximate Augmentation of Turbulent Law-of-the-Wall by Periodic Free-Stream Disturbances

Technical Report · Tue Dec 01 04:00:00 EST 2015

DOI:https://doi.org/10.2172/1331518· OSTI ID:1331518

Dechant, Lawrence J. ^[1]

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1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

We examine the role of periodic sinusoidal free-stream disturbances on the inner law law-of-the-wall (log-law) for turbulent boundary layers. This model serves a surrogate for the interaction of flight vehicles with atmospheric disturbances. The approximate skin friction expression that is derived suggests that free-stream disturbances can cause enhancement of the mean skin friction. Considering the influence of grid generated free stream turbulence in the laminar sublayer/log law region (small scale/high frequency) the model recovers the well-known shear layer enhancement suggesting an overall validity for the approach. The effect on the wall shear associated with the lower frequency due to the passage of the vehicle through large (vehicle scale) atmospheric disturbances is likely small i.e. on the order 1% increase for turbulence intensities on the order of 2%. The increase in wall pressure fluctuation which is directly proportional to the wall shear stress is correspondingly small.

• Research Organization: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 1331518
• Report Number(s): SAND2015--10713; 614994
• Country of Publication: United States
• Language: English

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