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van Eckeveld, A.C. (author), Westerweel, J. (author), Poelma, C. (author)Severe vibrations and sound production can occur in dry gas flow through corrugated pipes. The addition of very small amounts of liquid to the dry gas flow potentially mitigates these flow-induced vibrations (FIVs) and noise. The different mechanisms behind this whistling mitigation are studied in this work, where acoustic measurements are...journal article 2020
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Lau, Y.M. (author), Westerweel, J. (author), van de Water, W. (author)We use Faraday waves to measure interfacial tension σ between two immiscible fluids, with an interest in (ultra)low values of σ. The waves are excited by vertically oscillating the container in which the fluids reside. Using linear stability theory, we map out the accessible range of interfacial tensions. The smallest value (σmin ≈ 5 × 10-4 N...journal article 2020
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Calibration of multiple cameras for large-scale experiments using a freely moving calibration targetMuller, K. (author), Hemelrijk, C. K. (author), Westerweel, J. (author), Tam, D.S.W. (author)Abstract: Obtaining accurate experimental data from Lagrangian tracking and tomographic velocimetry requires an accurate camera calibration consistent over multiple views. Established calibration procedures are often challenging to implement when the length scale of the measurement volume exceeds that of a typical laboratory experiment. Here,...journal article 2020
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van Meerkerk, M. (author), Poelma, C. (author), Hofland, Bas (author), Westerweel, J. (author)We present an experimental study on the variation in wave impact location and present a mechanism for the development of free surface instabilities on the wave crest for repeatable plunging wave impacts on a vertical wall. The existence of free surface instabilities on an impacting wave is well known, but their characteristics and formation...journal article 2020
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van Meerkerk, M. (author), Poelma, C. (author), Westerweel, J. (author)In this work, we extend a planar laser-induced fluorescence method for free surface measurements to a three-dimensional domain using a stereo-camera system, a scanning light sheet, and a modified self-calibration procedure. The stereo-camera set-up enables a versatile measurement domain with self-calibration, improved accuracy, and redundancy...journal article 2020
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Kislaya, A. (author), Deka, Antaran (author), Veenstra, Peter (author), Tam, D.S.W. (author), Westerweel, J. (author)Abstract: In microscopic particle image velocimetry (micro-PIV), correlation averaging over multiple frames is often required, leading to a loss in temporal resolution, therefore limiting the measurement accuracy for unsteady flows. Here, we present a new PIV method suitable to study steady and unsteady laminar flows between parallel plates ...journal article 2020
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Gül, M. (author), Elsinga, G.E. (author), Westerweel, J. (author)This paper provides an experimental investigation on the internal shear layers and the edges of the uniform momentum zones (UMZs) in a turbulent pipe flow. The time-resolved stereoscopic particle image velocimetry data are acquired in the cross-section of the pipe, and span the range of Reynolds number Reτ=340--1259. In the first part of the...journal article 2020
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Tokgoz, S. (author), Elsinga, G.E. (author), Delfos, R. (author), Westerweel, J. (author)We report on the experimental investigation of the large-scale instantaneous flow structures in turbulent Taylor–Couette flow using tomographic particle image velocimetry. The results indicate three distinct regimes for counter-rotating flow within a shear Reynolds number range of 11000<ReS<47000 . Close to only inner cylinder rotation,...journal article 2020
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van den Berg, Joris (author), Jux, C. (author), Sciacchitano, A. (author), van de Water, W. (author), Westerweel, J. (author)The flow field around a full-scale swimmer’s hand model with varying thumb positions is investigated by robotic volumetric PIV. The experiment is conducted in the Open Jet Facility wind tunnel at TU Delft at 15m/s. Quantitative flow field information is constructed with 3D-PTV in a 120 liter volume, encompassing the full hand and arm. The effect...conference paper 2019
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Grift, E.J. (author), Tummers, M.J. (author), Overmars, E.F.J. (author), Westerweel, J. (author)We investigate the fluid motion generated by a moving rowing blade. The blade follows a complex path with rather strong acceleration and subsequent deceleration. The blade path is mimicked at a 1:2 scale in a large open-top water tank using a robot system. The tank is transparent, thus enabling full optical access for performing large-field...conference paper 2019
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Benschop, H.O.G. (author), Greidanus, A.J. (author), Delfos, R. (author), Westerweel, J. (author), Breugem, W.P. (author)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...journal article 2019
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Goyens, J. (author), Pourquie, M.J.B.M. (author), Poelma, C. (author), Westerweel, J. (author)The vestibular system in the inner ear senses angular head manoeuvres by endolymph fluid which deforms a gelatinous sensory structure (the cupula). We constructed computer models that include both the endolymph flow (using CFD modelling), the cupula deformation (using FEM modelling), and the interaction between both (using fluid–structure...journal article 2019
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Lintmeijer, Lotte L. (author), Onneweer, John P.T. (author), Hofmijster, Mathijs J. (author), Wijgergangs, Willem A. (author), De Koning, Hans (author), Clairbois, Bert (author), Westerweel, J. (author), Grift, E.J. (author), Tummers, M.J. (author), van Soest, A.M.J. (author)To analyze on-water rowing performance, a valid determination of the power loss due to the generation of propulsion is required. This power los can be calculated as the dot product of the net water force vector ( <sup>~</sup> F <sub>w;o</sub> ) and the time derivative of the position vector of the point at the blade where <sup>~</sup> F <sub...journal article 2019
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Grift, E.J. (author), Vijayaragavan, N. B. (author), Tummers, M.J. (author), Westerweel, J. (author)We present results on the drag on, and the flow field around, a submerged rectangular normal flat plate, which is uniformly accelerated to a constant target velocity along a straight path. The plate aspect ratio is chosen to be to resemble an oar blade in (competitive) rowing, the sport which inspired this study. The plate depth, i.e. the...journal article 2019
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Valori, V. (author), Elsinga, G.E. (author), Rohde, M. (author), Westerweel, J. (author), van der Hagen, T.H.J.J. (author)Abstract: The feasibility of particle image velocimetry (PIV) in a thermally convective supercritical fluid was investigated. Hereto a Rayleigh–Bénard convection flow was studied at pressure and temperature above their critical values. The working fluid chosen was trifluoromethane because of its experimentally accessible critical point. The...journal article 2019
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Charruault, F.T. (author), Greidanus, A.J. (author), Breugem, W.P. (author), Westerweel, J. (author)The present study introduces an experimental technique based on a Free Surface-Synthetic Schlieren (FS-SS) method in order to characterize free surfaces subjected to strong deformations. Current synthetic Schlieren methods are based on local image correlation and thus limited to rather weak image deformations, implying that they can only resolve...conference paper 2018
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Cornel, W.A. (author), Westerweel, J. (author), Poelma, C. (author)The challenge presented in this research is to determine the local volumetric bubble concentration (or void fraction) in the center of a microbubble cloud with limited optical access and without disturbing the flow. By applying defocused volumetric shadowgraphy to an aerated water column we were able to measure the characteristics of single...conference paper 2018
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van Meerkerk, M. (author), Poelma, C. (author), Westerweel, J. (author)A quasi three-dimensional stereo-camera measurement technique has been devised that is able to measure liquid free surface profiles, by scanning a light sheet. The technique will be applied to study the variability of impact pressure observed during wave impact in a newly developed experimental set-up. The set-up imposes severe optical (single...conference paper 2018
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Eisma, H.E. (author), Tam, D.S.W. (author), Westerweel, J. (author), van de Water, W. (author)We present results on the analysis of measurements on the dispersion of a contaminant in a turbulent boundary layer. The contaminant is a fluorescent dye (Rh.-B) that was introduced in a turbulent boundary layer (푅푅푒푒# = 3050) in a water channel. The velocity field was measured by means of tomographic PIV. Simultaneously, the concentration field...conference paper 2018
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Kislaya, A. (author), Deka, Antaran (author), Veenstra, Peter (author), Tam, D.S.W. (author), Westerweel, J. (author)In micro-PIV, reaching the optimum image density has always been difficult due to high displacement gradient, coagulation of particles at the inlet and due to particles adhering to the surface to name a few. The most widely used method is to take ensemble correlation average of multiple PIV images to extract the velocity field. However, this...conference paper 2018