Amplitude modulation of pressure in turbulent boundary layer

Tsuji, Yoshiyuki; Marušić, Ivan; Johansson, A.

doi:10.1016/j.ijheatfluidflow.2016.05.019

Cited by 22 publications

(21 citation statements)

References 26 publications

(41 reference statements)

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“…Such phase shifts between large and small scales have previously been reported (e.g. Bandyopadhyay & Hussain 1984;Jacobi & McKeon 2013;Tsuji, Marusic & Johansson 2016) and may relate to a preferential alignment of the small scales at the interfaces between large-scale structures. A precise description of the interaction, however, awaits further study.…”

Section: Amplitude Modulationsupporting

confidence: 75%

Drag forces on a bed particle in open-channel flow: effects of pressure spatial fluctuations and very-large-scale motions

2019

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The fluctuating drag forces acting on spherical roughness elements comprising the bed of an open-channel flow have been recorded along with synchronous measurements of the surrounding velocity field using stereoscopic particle image velocimetry. The protrusion of the target particle, equipped with a force sensor, was systematically varied between zero and one-half diameter relative to the hexagonally packed adjacent spheres. Premultiplied spectra of drag force fluctuations were found to have bimodal shapes with a low-frequency (${\approx}0.5~\text{Hz}$) peak corresponding to the presence of very-large-scale motions (VLSMs) in the turbulent flow. The high-frequency ($\gtrapprox 4~\text{Hz}$) region of the drag force spectra cannot be explained by velocity time series extracted from points around the particle, but instead appears to be dominated by the action of pressure gradients in the overlying flow field. For small particle protrusions, this high-frequency region contributes a majority of the drag force variance, while the relative importance of the low-frequency drag force fluctuations increases with increasing protrusion. The amplitude of high-frequency drag force fluctuations is modulated by the VLSMs irrespective of particle protrusion. These results provide some insight into the mechanics of bed particle stability and indicate that the optimum conditions for particle entrainment may occur when a low-pressure region embedded in the high-velocity portion of a VLSM overlays a particle.

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Section: Amplitude Modulationsupporting

confidence: 75%

Drag forces on a bed particle in open-channel flow: effects of pressure spatial fluctuations and very-large-scale motions

2019

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“…Interestingly, the pressure intensity p + 2 was also found to follow a similar log trend (e.g., Jiménez and Hoyas [5] and Tsuji et al [6]):…”

Section: Introductionmentioning

confidence: 60%

“…The error in the log fitting of Eqs. 5and (6) to the data and an investigation of the statistical convergence using premultiplied probability density functions (PDFs) are presented in Appendix B.…”

Section: Is the Double Factorialmentioning

confidence: 99%

“…Tsuji et al [6] carried out the measurements for the static pressure at different wall-normal locations within the turbulent boundary layer for a wide range of Reynolds number. From the spectral analysis of the pressure fluctuations upon applying Taylor's hypothesis, they observed the existence of a second peak in the premultiplied spectra.…”

Section: A Pressure Spectramentioning

confidence: 99%

“…Recently, Tsuji et al [6] attempted to interpret the structures behind the log trend of p + 2 . They divided the instantaneous pressure field with various levels of streamwise wavelength and observed the pressure intensity profiles for larger and smaller scales of motion than a cutoff wavelength.…”

Section: Introductionmentioning

confidence: 99%

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Pressure and spanwise velocity fluctuations in turbulent channel flows: Logarithmic behavior of moments and coherent structures

et al. 2019

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We study the logarithmic behavior of the pressure variance p + 2 from the datasets obtained from direct numerical simulations of turbulent channel flow for friction Reynolds number Re τ up to 4000. The higher-order moments of p were found to follow logarithmic behaviors at the same distances from the wall where p + 2 shows its log profile. The same results have been confirmed for the spanwise velocity fluctuations w at the same Reynolds numbers, with both p and w following a super-Gaussian behavior. The minimum Reynolds number for p + 2 and w + 2 log profiles to appear is Re τ ≈ 500, where flow structures O(h) or less were found to significantly contribute to these profiles. The configuration of the hairpin eddy structures obtained from the conditional sampling at different wall-normal locations showed a strong link between p and w fluctuations. Positive pressure fluctuations are located between the legs of the hairpin eddy, while the negative pressure fluctuations are consistent with the head part of the hairpin eddy. Positive and negative spanwise velocity fluctuations are strongly positioned with the legs of the hairpin eddy, consistent with the counter-rotating motion resulting from the eddy legs. The structures were also found to be geometrically self-similar such that their length and their width increase linearly with the distance from the wall.

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Influence of the Deep Spherical Dimple on the Pressure Field Under the Turbulent Boundary Layer

Voskoboinick

Turick²,

Voskoboinyk

et al. 2018

Advances in Intelligent Systems and Computing

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Amplitude modulation of pressure in turbulent boundary layer

Cited by 22 publications

References 26 publications

Drag forces on a bed particle in open-channel flow: effects of pressure spatial fluctuations and very-large-scale motions

Drag forces on a bed particle in open-channel flow: effects of pressure spatial fluctuations and very-large-scale motions

Pressure and spanwise velocity fluctuations in turbulent channel flows: Logarithmic behavior of moments and coherent structures

Influence of the Deep Spherical Dimple on the Pressure Field Under the Turbulent Boundary Layer

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