Taylor’s hypothesis in turbulent channel flow considered using a transport equation analysis

Geng, Chenhui; He, Guowei; Wang, Yinshan; Xu, Chunxiao; Lozano-Durán, Adrián; Wallace, J. M.

doi:10.1063/1.4908070

Cited by 66 publications

(71 citation statements)

References 41 publications

(56 reference statements)

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“…Therefore, this was the convection velocity used for the grid and noise resolution dependence study later. This was also in line with results from Geng et al (2015), who showed that for the logarithmic region of the boundary layer, using the mean velocity as the convection velocity is an adequately accurate assumption. For the EU and Table 2: Average correlation coefficient with varying convection velocities (ε u /U max = 1%, l + = 12) 2).…”

Section: Convection Velocity and Frame Time-separation Dependencesupporting

confidence: 78%

“…With the freestream noise subtraction mentioned above, the rms pressure distribution approximately follows the lower Re DNS dataset (which has a comparable Re θ with the experimental results), away from the wall. As expected, larger discrepancies can be seen closer to the wall, where the convection velocities likely deviate from the mean (Geng et al, 2015).…”

Section: Taylor's Hypothesis Approachmentioning

confidence: 52%

“…It is then clear that, Taylor's hypothesis is well satisfied, if the sum of the pressure, convective and viscous terms (enclosed in brackets) is negligible (Geng et al, 2015).…”

Section: Taylor's Hypothesis Approach (Th)mentioning

confidence: 99%

“…De Kat and Ganapathisubramani (2013) showed that using an in-plane filtered axial velocity in a turbulent jet as the convection velocity, yields more promising results for pressure, than using the mean. More recently, Geng et al (2015) tested the validity of using the mean as the convection velocity in the case of a turbulent channel and concluded that the assumption holds well in the logarithmic and outer layer but fails close to the wall. In the present study, different convection velocities will be tested, so a generalised form of Taylor's hypothesis, with a spatially changing convection velocity, U c = (U c ,V c ,W c ) will be used:…”

Section: Taylor's Hypothesis Approach (Th)mentioning

confidence: 99%

“…To examine the implications of using this hypothesis on the governing equations, we start from the momentum equation, rewriting it so as to include the chosen convection velocity (see Geng et al, 2015) and using Reynold's decomposition:…”

Section: Taylor's Hypothesis Approach (Th)mentioning

confidence: 99%

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Full-field pressure from snapshot and time-resolved volumetric PIV

2016

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This paper deals with pressure estimation from snapshot and time-resolved three component (3C) volumetric PIV data using Taylor's hypothesis, an Eulerian and a pseudo-Lagrangian approach. The Taylor's hypothesis approach has been shown to provide accurate results for pressure in the case of 3C planar PIV data with an appropriate choice of convection velocity (de Kat and Ganapathisubramani, 2013) and here we extend its use on 3C volumetric velocity snapshots. Application of the techniques to synthetic data shows that the Taylor's hypothesis approach performs best using the streamwise mean as the convection velocity and is affected the least by noise, while the Eulerian approach suffers the most. In terms of resolution, the pseudoLagrangian approach is the most sensitive. Its accuracy can be improved by increasing the frame time-separation when computing the material derivative, at the expense of volume loss from fluid parcels leaving the FOV. Comparison of the techniques on turbulent boundary layer data with DNS supports these observations and shows that the Taylor's hypothesis approach is the only way we can get pressure when time information is not present.

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Section: Convection Velocity and Frame Time-separation Dependencesupporting

confidence: 78%

Section: Taylor's Hypothesis Approachmentioning

confidence: 52%

“…It is then clear that, Taylor's hypothesis is well satisfied, if the sum of the pressure, convective and viscous terms (enclosed in brackets) is negligible (Geng et al, 2015).…”

Section: Taylor's Hypothesis Approach (Th)mentioning

confidence: 99%

Section: Taylor's Hypothesis Approach (Th)mentioning

confidence: 99%

Section: Taylor's Hypothesis Approach (Th)mentioning

confidence: 99%

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Full-field pressure from snapshot and time-resolved volumetric PIV

2016

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Introduction

Liu,

Cai

2023

Inverse Problems in Global Flow Diagnostics

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A new method for measuring turbulent heat fluxes using PIV and fast-response cold-wires

2015

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In a laboratory setting, heat fluxes are generally acquired using a combination of hot-and cold-wire anemometry, where the probes are placed in close proximity to each other and sampled simultaneously to obtain fluctuations in velocity and temperature. Hot-wires, however, are sensitive both to velocity and to temperature, and so, if the flow has mean velocity and temperature gradients, as in a boundary layer, extensive calibrations are required. In addition, if the wall-normal heat flux wθ were needed, as is often the case, crossed wires would also be required, adding further complexity (w is the wall-normal velocity fluctuation, θ is the local temperature fluctuation, and the overline signifies an ensemble average). In addition, fluctuating temperature measurements obtained using cold-wires often suffer from significant frequency response limitations due to the thermal inertia of the probe and conduction to the prongs (Smits et al. 1978;Smits and Perry 1981;Arwatz et al. 2013).A limited number of previous studies have employed laser Doppler anemometry (LDA) in combination with a cold-wire to measure the heat fluxes at a single point while avoiding complex calibration requirements (see, for example, Thole and Bogard 1994;Heist and Castro 1998). Here, we outline a new method to obtain turbulent heat flux data using a combination of particle image velocimetry (PIV) and a nanoscale cold-wire specifically designed for improved frequency response (Fan et al. 2015). In its simplest form, this method gives the wall-normal (wθ) and streamwise turbulent heat fluxes (uθ) at a single point, using the velocities measured immediately adjacent to the cold-wire probe, with one sample per PIV image, as with previous LDA measurements. Crucially, however, this new method also provides spatial velocity information and thus a direct measure of the streamwise coherence of the velocity and temperature fields, so that the streamwise integral length scales can be Abstract A new method for measuring turbulent heat fluxes using a combination of particle image velocimetry and a nanoscale fast-response cold-wire is tested by examining a rough-wall turbulent boundary layer subject to weakly stable stratification. The method has the advantages of simple calibration and setup, as well as providing spatial correlations of velocity and temperature and their associated integral length scales. The accuracy of using Taylor's hypothesis when employing a large field of view is investigated. Heat flux, velocity-temperature correlation coefficients and turbulent Prandtl number profiles, as well as spatial velocity and temperature correlations, are presented.

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Taylor’s hypothesis in turbulent channel flow considered using a transport equation analysis

Cited by 66 publications

References 41 publications

Full-field pressure from snapshot and time-resolved volumetric PIV

Full-field pressure from snapshot and time-resolved volumetric PIV

Introduction

A new method for measuring turbulent heat fluxes using PIV and fast-response cold-wires

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