The Effect Of Particle Lag On Statistics Of Hypersonic Turbulent Boundary Layers Subject To Pressure Gradients


For the current work, we analyzed the effects of particle tracing on a (formula presented) = 4.9 turbulent boundary layer subjected to zero and strong favorable pressure gradients, wherein synthetic particle images were generated from the Lagrangian particle tracking using data from a direct numerical simulation (DNS) and processed with standard particle image velocimetry (PIV) cross-correlation techniques. The study showed that, with the particle Stokes number fixed at the experimental value of about 0.1, a better match in the wall-normal and shear components of the Reynolds stresses between the PIV and DNS was achieved when the PIV spatial resolution was increased from 32 x 32 pixels to 16 x 16 pixels. The improved accuracy of the Reynolds stress at a spatial resolution finer than the experiment suggested that the lower magnitudes of the wall-normal and shear Reynolds stresses reported by Tichenor et al. [1] were likely caused by a lack of spatial resolution rather than the particle inertia effects. A further analysis of the effects of particle inertia and PIV spatial resolution revealed that the sensitivity of the Reynolds stresses to particle inertia increased with the PIV spatial resolution, and an overreduction in the PIV window size led to large spurious overshoots in Reynolds stresses and worsening comparisons with the DNS.


Mechanical and Aerospace Engineering


Office of Naval Research, Grant N00014-20-1-2194

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Article - Conference proceedings

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Publication Date

01 Jan 2022