A scheme to correct the influence of calibration misalignment for cross-wire probes in turbulent shear flows

Deshpande, Rahul; Monty, Jason; Marušić, Ivan

doi:10.1007/s00348-020-2918-8

Cited by 6 publications

(6 citation statements)

References 31 publications

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“…For comparison purposes, six closed channel flow cases were also considered (as summarized in table 1), including three DNS cases at , 1000, 2000 with normal streamwise domain sizes of (Lee & Moser 2015, 2019), one DNS case at with a very long streamwise domain size of (Lozano-Durán & Jiménez 2014), and two experimental cases at (Deshpande et al. 2020) and 1600 (Balakumar 2005; Balakumar & Adrian 2007).…”

Section: Datasets and Methodologymentioning

confidence: 99%

“…The two experimental cases at =1000 (Deshpande et al. 2020) and 1600 (Balakumar 2005; Balakumar & Adrian 2007) (denoted as CCF1000 and CCF1600) are fully time-resolved velocity measurements performed with hot-wire anemometry (HWA), from which the streamwise and wall-normal velocity components are simultaneously measured. Accordingly, the streamwise (co-)spectra of the streamwise and wall-normal velocity fluctuations were obtained.…”

Section: Datasets and Methodologymentioning

confidence: 99%

“…the widely used single point HWA measurements in abundant studies, including the CCF1000 (Deshpande et al. 2020) and CCF1600 (Balakumar 2005; Balakumar & Adrian 2007) experimental cases considered herein), the local mean velocity was the only accessible choice. Abundant studies have demonstrated that is a good surrogate of that could give sufficient accurate spectra results, except in the near-wall region (de Kat & Ganapathisubramani 2015; Squire et al.…”

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confidence: 99%

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Contributions of different scales of turbulent motions to the mean wall-shear stress in open channel flows at low-to-moderate Reynolds numbers

et al. 2021

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Section: Datasets and Methodologymentioning

confidence: 99%

Section: Datasets and Methodologymentioning

confidence: 99%

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confidence: 99%

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Contributions of different scales of turbulent motions to the mean wall-shear stress in open channel flows at low-to-moderate Reynolds numbers

et al. 2021

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“…Availability of high Re τ datasets in laboratory environments over time [24][25][26][27], however, has confirmed that contribution to the bulk production (at high Re τ ) comes from the logarithmic (log) region [28]. Further, the ability to simulate experimental conditions with high fidelity direct numerical simulation datasets [29][30][31] has revealed the possibility of significant measurement inaccuracies originating from poor spatial resolution while using cross-wire probes (or X-probes) in the near-wall region. These studies have inspired the development of miniature X-wire probes with sufficiently good resolution [26,27,29,31] for measuring velocity statistics in the high Re τ log-region.…”

Section: Introductionmentioning

confidence: 99%

“…Further, the ability to simulate experimental conditions with high fidelity direct numerical simulation datasets [29][30][31] has revealed the possibility of significant measurement inaccuracies originating from poor spatial resolution while using cross-wire probes (or X-probes) in the near-wall region. These studies have inspired the development of miniature X-wire probes with sufficiently good resolution [26,27,29,31] for measuring velocity statistics in the high Re τ log-region. The availability of these high-fidelity datasets across a range of Re τ has also permitted application of several post-processing algorithms (e.g., spectral linear stochastic estimation (SLSE) [32,33]) to present empirical evidence [34,35] in support of Townsend's attached eddy hypothesis (discussed briefly ahead in Section 1).…”

Section: Introductionmentioning

confidence: 99%

Characterising Momentum Flux Events in High Reynolds Number Turbulent Boundary Layers

Deshpande

Marušić

2021

Fluids

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The momentum flux in a canonical turbulent boundary layer is known to have a time-series signature that is characterised by a highly intermittent variation, which includes very short periods of intense flux activity. Here, we study the variation in these flux signal characteristics across almost a decade of flow Reynolds number (Reτ) by analysing datasets acquired using miniature cross-wire probes with matched spatial resolution. The analysis is facilitated by conditionally sampling the signal based on the quadrant (Qi; i = 1–4) and magnitude of the flux, revealing fractional cumulative contribution from Q4 to increase at a much faster rate than from Q2 with Reτ. An episodic description of the flux signal is subsequently undertaken, which associates this rapid increase in Q4 contributions with the emergence of extreme and rare flux events with Reτ. The same dataset is also used to test Townsend’s hypothesis on the active and inactive components of the momentum flux, which are obtained for the first time by implementing a spectral linear stochastic estimation-based decomposition methodology. While the active component is found to be the dominant contributor to the mean momentum flux consistent with Townsend’s hypothesis, the inactive component is found to be small but non-zero, owing to the non-linear interactions associated with the modulation phenomenon. Finally, an episodic description of the active and inactive momentum flux signal is undertaken to highlight the starkly different time series characteristics of the two flux components. The inactive flux signal is found to comprise individual statistically significant events associated with all four quadrants, leading to a small net contribution to the total flux.

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Characteristics of very-large-scale motions in gradually varied open-channel flows upstream of a run-of-river dam

et al. 2022

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The gradually varied open-channel flows (OCF) upstream of a run-of-river (RoR) dam are ubiquitous in natural rivers. In this flow type, the velocity profile shows some similarities to that in uniform open-channel flows, but the turbulence intensity and Reynolds shear stress are slightly greater. However, the presence and properties of very-large-scale motions (VLSMs) in such flows are still unclear. To fill this research gap, time-resolved particle image velocimetry measurements were performed upstream of a modeled RoR dam in an open-channel flume. Based on pre-multiplied spectra analysis, statistical evidence of the presence of VLSMs in the flow type is reported for the first time. The results reveal that although the typical streamwise wavelength of VLSMs in such gradually varied OCF is similar to that in other flows, such as turbulent boundary layers, closed-channel flows, pipe flows, and uniform OCF, the VLSMs in the present gradually varied OCF are stronger and contribute more streamwise turbulent kinetic energy as well as Reynolds shear stress than other flows.

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A scheme to correct the influence of calibration misalignment for cross-wire probes in turbulent shear flows

Cited by 6 publications

References 31 publications

Contributions of different scales of turbulent motions to the mean wall-shear stress in open channel flows at low-to-moderate Reynolds numbers

Contributions of different scales of turbulent motions to the mean wall-shear stress in open channel flows at low-to-moderate Reynolds numbers

Characterising Momentum Flux Events in High Reynolds Number Turbulent Boundary Layers

Characteristics of very-large-scale motions in gradually varied open-channel flows upstream of a run-of-river dam

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