Integrating Mach–Zehnder interferometry with TPIV to measure the time-resolved deformation of a compliant wall along with the 3D velocity field in a turbulent channel flow

Cao, Zhang; Miorini, Rinaldo L.; Katz, Joseph

doi:10.1007/s00348-015-2072-x

Cited by 21 publications

(25 citation statements)

References 55 publications

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“…These findings may explain why recent numerical studies consistently report either an increase in drag or a statistically unchanged flow field in the presence of travelling wave-like wall deformations (Xu et al 2003;Fukagata et al 2008;Rosti & Brandt 2017;Xia et al 2017). More recently, Zhang, Miorini & Katz (2015), Zhang et al (2017) have reported pioneering experiments that capture compliant wall deformations and turbulent velocity field in a water channel simultaneously. These experiments confirmed unequivocally the existence of travelling waves on the surface.…”

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confidence: 85%

Active and passive in-plane wall fluctuations in turbulent channel flows

et al. 2019

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Compliant walls offer the tantalising possibility of passive flow control. This paper examines the mechanics of compliant surfaces driven by wall shear stresses, with solely in-plane velocity response. We present direct numerical simulations of turbulent channel flows at low (Re τ ≈ 180) and intermediate (Re τ ≈ 1000) Reynolds numbers. In-plane spanwise and streamwise active controls proposed by Choi et al. (J. Fluid Mech., vol. 262, 1994, pp. 75-110) are revisited in order to characterise beneficial wall fluctuations. An analytical framework is then used to map the parameter space of the proposed compliant surfaces. The direct numerical simulations show that large-scale passive streamwise wall fluctuations can reduce friction drag by at least 3.7 ± 1 %, whereas even small-scale passive spanwise wall motions lead to considerable drag penalty. It is found that a well-designed compliant wall can theoretically exploit the drag-reduction mechanism of an active control; this may help advance the development of practical active and passive control strategies for turbulent friction drag reduction.

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confidence: 85%

Active and passive in-plane wall fluctuations in turbulent channel flows

et al. 2019

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“…Recording the interferogram on film, their data are not time resolved. Recently, Zhang, Miorini & Katz (2015) and Zhang et al . (2017) have introduced a time-resolved system, which simultaneously measures the two-dimensional (2-D) surface deformation using Mach–Zehnder interferometry (MZI), and the 3-D velocity field using tomographic particle image velocimetry.…”

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confidence: 96%

“…In our above-mentioned previous experimental study of turbulent channel flow over a compliant wall (Zhang et al . 2015, 2017), the deformation amplitude is much smaller than one wall unit, hence it predominantly involves one-way coupling between the flow and deformation. In the present study, the material properties and coating thickness are selected to establish two-way coupling based on theoretical predictions of the response of compliant coatings to pressure perturbations.…”

Section: Introductionmentioning

confidence: 99%

On the interaction of a compliant wall with a turbulent boundary layer

2020

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“…Zhang et al (2017) investigated a compliant coating in a turbulent channel flow at Re τ = 2300. They report simultaneous measurements of the time-resolved, three-dimensional flow field (using particle image velocimetry (PIV)) and the twodimensional surface deformation (using Mach-Zehnder interferometry (Zhang, Miorini & Katz 2015)). Their compliant coating is relatively stiff: the root-mean-square (r.m.s.)…”

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Deformation of a linear viscoelastic compliant coating in a turbulent flow

et al. 2018

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We investigate the deformation of a linear viscoelastic compliant coating in a turbulent flow for a wide range of coating parameters. A one-way coupling model is proposed in which the turbulent surface stresses are expressed as a sum of streamwise-travelling waves with amplitudes determined from the stress spectra of the corresponding flow over a rigid wall. The analytically calculated coating deformation is analysed in terms of the root-mean-square (r.m.s.) surface displacement and the corresponding point frequency spectra. The present study systematically investigates the influence of five coating properties namely density, stiffness, thickness, viscoelasticity and compressibility. The surface displacements increase linearly with the fluid/solid density ratio. They are linearly proportional to the coating thickness for thin coatings, while they become independent of the thickness for thick coatings. Very soft coatings show resonant behaviour, but the displacement for stiffer coatings is proportional to the inverse of the shear modulus. The viscoelastic loss angle has only a significant influence when resonances occur in the coating response, while Poisson’s ratio has a minor effect for most cases. The modelled surface displacement is qualitatively compared with recent measurements on the deformation of three different coatings in a turbulent boundary-layer flow. The model predicts the order of magnitude of the surface displacement, and it captures the increase of the coating displacement with the Reynolds number and the coating softness. Finally, we propose a scaling that collapses all the experimental data for the r.m.s. of the vertical surface displacement onto a single curve.

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Integrating Mach–Zehnder interferometry with TPIV to measure the time-resolved deformation of a compliant wall along with the 3D velocity field in a turbulent channel flow

Cited by 21 publications

References 55 publications

Active and passive in-plane wall fluctuations in turbulent channel flows

Active and passive in-plane wall fluctuations in turbulent channel flows

On the interaction of a compliant wall with a turbulent boundary layer

Deformation of a linear viscoelastic compliant coating in a turbulent flow

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