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Drost, S. (author), Westerweel, J. (author)In this paper, we describe a novel approach to determine the flow behavior index of a power-law fluid by means of a microfluidic device. The concept of this method is based on a mathematical analysis by Aronsson and Janfalk [Eur. J. Appl. Math. 3, 343–366 (1992)] of Hele-Shaw flow of power-law liquids. We implement this approach by driving a non...journal article 2013
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Fiscaletti, D. (author), Elsinga, G.E. (author), Ganapathisubramani, B. (author), Westerweel, J. (author)This work involves the large-scale amplitude and frequency modulation of the small-scale motions in fullydeveloped turbulence of a high Reynolds number jet. The scales responsible for the production of turbulent kinetic energy (large scales), and those responsible for its viscous dissipation (small scales) are extracted from time series of...conference paper 2013
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Tokgoz, S. (author), Elsinga, G.E. (author), Westerweel, J. (author)Time-resolved tomographic PIV was used to investigate the time evolution of turbulent flow structures in Taylor-Couette flow. Turbulence is created by the shear due to exact counter rotation of the cylinders, where the mean velocity is zero in the bulk flow. This enables to observe the structures longer than many other turbulent flow types,...conference paper 2013
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Fiscaletti, D. (author), Elsinga, G.E. (author), Westerweel, J. (author)The present work involves the investigation of the fine scale motions in the turbulent region of a high Reynolds number air jet. In the fully developed region of the jets, the small scales of turbulence are assumed to be isotropic, and expected to contain elongated vortices (worms), whose diameter scales with the Kolmogorov length scale. Aimed...conference paper 2013
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Tokgoz, S. (author), Elsinga, G.E. (author), Westerweel, J. (author)Time-resolved tomographic PIV was used to investigate the time evolution of turbulent flow structures in Taylor-Couette flow. Turbulence is created by the shear due to exact counter rotation of the cylinders, where the mean velocity is zero in the bulk flow. This enables to observe the structures longer than many other turbulent flow types,...conference paper 2013
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Hussong, J. (author), Lindken, R. (author), Faulhammer, P. (author), Noreikat, K. (author), Sharp, K.V. (author), Kummer, W. (author), Westerweel, J. (author)To date, there is only a fragmentary understanding of the fundamental mechanisms of airway mucociliary transport. Application of the latest measurement techniques can aid in deciphering the complex interplay between ciliary beat and airway surface liquid (ASL) transport. In the present study, direct, quasi-simultaneous measurements of the cilia...journal article 2013
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Eisma, H.E. (author), Elsinga, G.E. (author), Westerweel, J. (author)Interfaces are commonly observed features of turbulent flows. Previous research has indicated the significance of these interfaces on the overall dynamics of the turbulent flow [1]. The current research focuses on both the external Turbulent/Non-Turbulent (T/NT) interface as well as internal layers that are present in an experimentally...conference paper 2013
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Greidanus, A.J. (author), Delfos, R. (author), Westerweel, J. (author)The largest part of hydrodynamic drag during rowing, sailing or canoeing is the turbulent skin friction (80-90%). Higher velocities can be achieved by reducing the friction drag as a result of surface treatment. This research focuses on the development, characterization, and testing of drag-reducing surfaces, like nano- and micro-structured...journal article 2012
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Poelma, C. (author), Kloosterman, A. (author), Hierck, B.P. (author), Westerweel, J. (author)Imaging-based blood flow measurement techniques, such as particle image velocimetry, have become an important tool in cardiovascular research. They provide quantitative information about blood flow, which benefits applications ranging from developmental biology to tumor perfusion studies. Studies using these methods can be classified based on...journal article 2012
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- Tokgoz, S. (author), Elsinga, G.E. (author), Delfos, R. (author), Westerweel, J. (author) journal article 2012
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Elsinga, G.E. (author), Westerweel, J. (author)Tomographic-PIV was used to measure the boundary layer transition forced by a zigzag trip. The resulting instantaneous three-dimensional velocity distributions are used to quantitatively visualize the flow structures. They reveal undulating spanwise vortices directly behind the trip, which break up into individual arches and then develop into...journal article 2012
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Markesteijn, A.P. (author), Hartkamp, R. (author), Luding, S. (author), Westerweel, J. (author)The viscosity-temperature relation is determined for the water models SPC/E, TIP4P, TIP4P/Ew, and TIP4P/2005 by considering Poiseuille flow inside a nano-channel using molecular dynamics. The viscosity is determined by fitting the resulting velocity profile (away from the walls) to the continuum solution for a Newtonian fluid and then compared...journal article 2012
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- Elsinga, G.E. (author), Poelma, C. (author), Schröder, A. (author), Geisler, R. (author), Scarano, F. (author), Westerweel, J. (author) journal article 2012
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Trip, R. (author), Kuik, D.J. (author), Westerweel, J. (author), Poelma, C. (author)The transitional regime of a sinusoidal pulsatile flow in a straight, rigid pipe is investigated using particle image velocimetry. The main aim is to investigate how the critical Reynolds number is affected by different pulsatile conditions, expressed as the Womersley number and the oscillatory Reynolds number. The transition occurs in the...journal article 2012
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- Zverkhovskyi, O. (author), van Terwisga, T.J.C. (author), Delfos, R. (author), Westerweel, J. (author) conference paper 2012
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Greidanus, A.J. (author), Delfos, R. (author), Westerweel, J. (author)We use a Taylor-Couette facility to study the drag reducing effects of commercial surface products at high shear Reynolds numbers (Res) under perfect couter-rotating conditions (riwi=rowo). The correlation between torque contribution of the von Karman flow and shear Reynolds number is investigated. At this moment no significant drag changes are...conference paper 2011
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Harleman, M.J.W. (author), Delfos, R. (author), Van Terwisga, T.J.C. (author), Westerweel, J. (author)Dispersion and preferential concentration of small, low Stokes number bubbles in horizontal turbulent channel flow is studied by DNS and experiments. A DNS of turbulent channel flow at Re = 360 with Lagrangian tracking of one-way coupled bubbles (d < n, St = 1.3×10?3) shows that equilibrium bubble concentration profiles can be described by a...conference paper 2011
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Warncke, N.G.W. (author), Delfos, R. (author), Ooms, G. (author), Westerweel, J. (author)In this work we study the preferential concentration of small particles in the turbulent wake behind a spherical-cap object. We present a model predicting the mean particle concentration in the near-wake as a function of the characteristic Stokes number of the problem, the turbulence level and the Froude number. We compare the model with our...conference paper 2011
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Hussong, J. (author), Breugem, W.P. (author), Westerweel, J. (author)In this numerical study we investigate the flow induced by metachronal coordination between beating cilia arranged in a densely packed layer by means of a continuum model. The continuum approach allows us to treat the problem as two-dimensional as well as stationary, in a reference frame moving with the speed of the metachronal wave. The model...journal article 2011
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Koschatzky, V. (author), Westerweel, J. (author), Boersma, B.J. (author)The aim of the present study is to compare two different acoustic analogies applied to time-resolved particle image velocimetry (PIV) data for the prediction of the acoustic far-field generated by the flow over a rectangular cavity. We consider the model problem of sound radiating from an open, two-dimensional, shallow cavity with an aspect...journal article 2011