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Gotfredsen, Erik (author), Kunoy, Jens D. (author), Mayer, Stefan (author), Poelma, C. (author), Westerweel, J. (author), Meyer, Knud Erik (author)The effect of pulsations in a catalyst converter is investigated with the aim of determining if a steady flow captures the same physical phenomena as the pulsating flow. For this specific case, guide vanes are mounted in the sudden expansion to obtain a uniform inlet flow to the catalytic layers. The test rig is successfully validated against...conference paper 2018
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Muller, K. (author), Tam, D.S.W. (author), Westerweel, J. (author)Obtaining accurate experimental data from Lagrangian tracking and tomographic velocimetry requires an accurate and consistent camera calibration over multiple views. At length-scales that span beyond the laboratory environment obtaining a camera calibration can be challenging. Combining tools developed in computer vision and non-linear camera...conference paper 2018
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van Eckeveld, A.C. (author), Gotfredsen, E. (author), Westerweel, J. (author), Poelma, C. (author)Two-phase flow in ribbed or corrugated pipes is of interest in many industrial applications. Experiments are performed to assess the flow regime characteristics in upward annular flow through vertical smooth and corrugated pipes. From high speed recordings, the flow regime and temporal film characteristics are obtained. A novel implementation...journal article 2018
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van Hout, R.L.H. (author), Eisma, H.E. (author), Elsinga, G.E. (author), Westerweel, J. (author)In many applications, finite-sized particles are immersed in a turbulent boundary layer (TBL) and it is of interest to study wall effects on the instantaneous shedding of turbulence structures and associated mean velocity and Reynolds stress distributions. Here, 3D flow field dynamics in the wake of a prototypical, small sphere (D+=50, 692<...journal article 2018
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Gül, M. (author), Elsinga, G.E. (author), Westerweel, J. (author)This paper describes the hysteresis in the torque for Taylor–Couette flow in the turbulent flow regime for different shear Reynolds numbers, aspect ratios and boundary conditions. The hysteresis increases with decreasing shear Reynolds number and becomes more pronounced as the aspect ratio is increased from 22 to 88. Measurements conducted in...journal article 2018
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Eisma, H.E. (author), Tomas, J.M. (author), Pourquie, M.J.B.M. (author), Elsinga, G.E. (author), Jonker, H.J.J. (author), Westerweel, J. (author)Simultaneous particle-image velocimetry and laser-induced fluorescence combined with large-eddy simulations are used to investigate the flow and pollutant dispersion behaviour in a rural-to-urban roughness transition. The urban roughness is characterized by an array of cubical obstacles in an aligned arrangement. A plane fence is added one...journal article 2018
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van Houwelingen, Josje (author), Antwerpen, Raf M. (author), Holten, Ad P.C. (author), Grift, E.J. (author), Westerweel, J. (author), Clercx, Herman J.H. (author)In this paper a video-based method to automatically track instantaneous velocities of a swimmer is presented. Single cameras were used to follow a marker (LED) attached to the body. The method is inspired by particle tracking techniques, traditionally used in the field of fluid dynamics, to measure local velocities of a fluid flow. During the...journal article 2018
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- Valori, V. (author), Elsinga, G.E. (author), Rohde, M. (author), Tummers, M.J. (author), Westerweel, J. (author), van der Hagen, T.H.J.J. (author) journal article 2017
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Tomas, J.M. (author), Eisma, H.E. (author), Pourquie, M.J.B.M. (author), Elsinga, G.E. (author), Jonker, H.J.J. (author), Westerweel, J. (author)Both large-eddy simulations (LES) and water-tunnel experiments, using simultaneous stereoscopic particle image velocimetry and laser-induced fluorescence, have been used to investigate pollutant dispersion mechanisms in regions where the surface changes from rural to urban roughness. The urban roughness was characterized by an array of...journal article 2017
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van Eckeveld, A.C. (author), Westerweel, J. (author), Poelma, C. (author)When a corrugated pipe is subject to a dry gas flow, high amplitude sound can be produced (so-called ‘whistling’). It was shown previously that liquid addition to corrugated pipe flow has the ability to reduce sound production. Small amounts of liquid are sufficient to mitigate whistling entirely. One of the mitigation mechanisms, cavity...journal article 2017
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Pennings, P.C. (author), Westerweel, J. (author), Van Terwisga, T.J.C. (author)The goal of this study is to test the hypothesis that the resonance of a tip vortex cavity is responsible for high-amplitude broadband pressure-fluctuations, typically between 40 and 70 Hz,Hz, for a full scale propeller. This is achieved with a model propeller in a cavitation tunnel. Simultaneous high-speed video shadowgraphy and sound...journal article 2016
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- Westerweel, J. (author) journal article 2016
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Greidanus, A.J. (author), Delfos, R. (author), Westerweel, J. (author)The flow motions in the turbulent boundary layer between water and a rowing boat initiate a turbulent skin friction. Reducing this skin friction results in better rowing performances. A Taylor-Couette (TC) facility was used to verify the power losses due to velocity fluctuations P<sub>V′</sub> in relation to the total power, as a function of...conference paper 2016
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Kuyt, C.B. (author), Greidanus, A.J. (author), Westerweel, J. (author)The objective of this study was to determine the advantage of the application of speedstrips to rowing oars for a lightweight single sculler. The research method comprehended three steps: (1) the analysis of the rowing oar movement, (2) the determination of the change in drag and (3) the composition of a rowing model to establish the...conference paper 2016
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Pennings, P.C. (author), Westerweel, J. (author), Van Terwisga, T.J.C. (author)The design of an efficient propeller is limited by the harmful effects of cavitation. The insuffcient understanding of the role of vortex cavitation in noise and vibration reduces the maximum effciency by a necessary safety margin. The aim in the present study is to directly relate propeller cavitation sound to tip vortex cavity dynamics. This...conference paper 2015
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Costa, P. (author), Boersma, B.J. (author), Westerweel, J. (author), Breugem, W.P. (author)We present a collision model for particle-particle and particle-wall interactions in interface-resolved simulations of particle-laden flows. Three types of interparticle interactions are taken into account: (1) long- and (2) short-range hydrodynamic interactions, and (3) solid-solid contact. Long-range interactions are incorporated through an...journal article 2015
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Pennings, P.C. (author), Westerweel, J. (author), Van Terwisga, T.J.C. (author)Models for the center frequency of cavitating-vortex induced pressure-fluctuations, in a flow around propellers, require knowledge of the vortex strength and vapor cavity size. For this purpose, stereoscopic particle image velocimetry (PIV) measurements were taken downstream of a fixed half-wing model. A high spatial resolution is required and...journal article 2015
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Alidai, A. (author), Greidanus, A.J. (author), Delfos, R. (author), Westerweel, J. (author)The transition from the laminar to the turbulent regime in linearly stable shear flows, for example, pipe and plane Couette flows, occurs abruptly with no precursor. The evolution of turbulent spots has been studied to better understand the dynamics of this transition and the onset of turbulence. These studies have mostly focused on pipe flows...journal article 2015
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Friction measurements were performed in a Taylor-Couette setup. Drag reduction was obtained with a riblet surface and indicated a drag reduction for a wide range of shear Reynolds numbers, with a maximum of 5.3% at Re_s=47000 (s+=14). Tomographic PIV verified that the friction coefficients are strongly related to the flow regimes and structures....conference paper 2015
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Eisma, J. (author), Westerweel, J. (author), Elsinga, G.E. (author)Experimental research is presented on the characteristics of interfaces and internal layers that are present in a turbulent boundary layer (TBL). Both the turbulent non-turbulent interface (T/NT) and internal shear layers are detected in snapshots of the stereo-PIV data. It turns out that the internal layers exhibit similar characteristics...conference paper 2015