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Hehner, Marc T. (author), Gatti, Davide (author), Kotsonis, M. (author), Kriegseis, Jochen (author)Two different plasma actuation strategies for producing near-wall flow oscillations, namely the burst-modulation and beat-frequency mode, are characterized with planar particle image velocimetry in quiescent air. Both concepts are anticipated to work as non-mechanical surrogates of oscillating walls aimed at turbulent flow drag reduction,...journal article 2022
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Belligoli, Z. (author)The continuous increase in the number of flights in the last decades caused a steepgrowth of aviation-related pollution to the point that the aviation sector is responsible for3% of the global greenhouse gas emissions. Regulators have been slow at catching up withthis problem, and stringent emission targets have been put in place only very...doctoral thesis 2021
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Reurings, C. (author), Koussios, S. (author), Bergsma, O.K. (author), Vergote, K. (author), Paeshuyse, L. (author), Benedictus, R. (author)A realistic wear test was developed for porous thermal insulation systems exposed to high temperature turbulent gas flow, because it is essential for the development of existing and new concepts of such insulation and therefore also for the performance of processes that depend on such insulation. Wear is crucial and often dominant for the...journal article 2021
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Samie, M. (author), Baars, W.J. (author), Rouhi, A. (author), Schlatter, P. (author), Örlü, R. (author), Marusic, I. (author), Hutchins, N. (author)Opposition-control of the energetic cycle of near wall streaks in wall-bounded turbulence, using numerical approaches, has shown promise for drag reduction. For practical implementation, real-time opposition control is only realizable if there is a degree of coherence between the turbulent velocities passing a sensor and the target point...journal article 2020
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Greidanus, A.J. (author)This thesis describes the investigation of the dynamics of turbulent shear flows over non-smooth surfaces. The research was conducted in two parts, related to the experimental facility used in combination with the applied functional surface. The first part describes the experiments of a turbulent Taylor-Couette flow over a...doctoral thesis 2020
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Nakate, P.A. (author), Lahaye, D.J.P. (author), Vuik, Cornelis (author), Talice, Marco (author)The emissions from the industrial furnaces impact the environment. Among the various factories, those having anode baking furnaces are working on reducing the pollutant emissions. The aerodynamics in the furnace influences the emissions due to the high dependence of combustion and radiation phenomena on the mixing characteristics. Therefore,...journal article 2020
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Truong Hong, S. (author), Phan, K.L. (author), Stive, M.J.F. (author), Uijttewaal, W.S.J. (author)The significant defensive role of vegetation in general and mangroves in particular for coastal and estuarine regions has been increasingly recognized. However, understanding the shallow flow field in and around the region of vegetation is still limited. In order to gain more insight, a laboratory experiment of a vegetated compound channel...book chapter 2020
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Kaller, Thomas (author), Pasquariello, Vito (author), Hickel, S. (author), Adams, Nikolaus A. (author)We present well-resolved large-eddy simulations of turbulent flow through a straight, high aspect ratio cooling duct operated with water at a bulk Reynolds number of Re<sub>b</sub> = 110 × 10<sup>3</sup> and an average Nusselt number of Nuxz = 371. The geometry and boundary conditions follow an experimental reference case and good agreement...journal article 2019
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Broekema, Y.B. (author), Labeur, R.J. (author), Uijttewaal, W.S.J. (author)Flow separation and its control have been the subject of intensive research for decades. Flow separation occurs when the boundary layer loses contact with the associated confining wall, which is usually caused by a pressure gradient acting against the local flow direction. Numerous strategies exist to control flow separation, and in this...journal article 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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Peeters, J.W.R. (author), Rohde, M. (author)A new friction-heat transfer analogy for the prediction of heat transfer to turbulent fluids at supercritical pressure is presented. This analogy is based on the observation that the predominent events that determine the turbulent heat flux known as hot ejections and cold sweeps have different thermophysical properties. This observation is...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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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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Elsinga, G.E. (author), Ishihara, T. (author), Goudar Vishwanathappa, M. (author), da Silva, C.B. (author), Hunt, J.C.R. (author)The scaling of turbulent motions is investigated by considering the flow in the eigenframe of the local strain-rate tensor. The flow patterns in this frame of reference are evaluated using existing direct numerical simulations of homogeneous isotropic turbulence over a Reynolds number range from up to 1131, and also with reference to data for...journal article 2017
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Peeters, J.W.R. (author), Pecnik, Rene (author), Rohde, M. (author), van der Hagen, T.H.J.J. (author), Boersma, B.J. (author)Heated or cooled fluids at supercritical pressure show large variations in thermophysical properties, such as the density, dynamic viscosity and molecular Prandtl number, which strongly influence turbulence characteristics. To investigate this, direct numerical simulations were performed of a turbulent flow at supercritical pressure (CO2 at 8...journal article 2016
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De Wit, L. (author)3D CFD simulations, lab experiments and field measurements are used to get more understanding of the turbulent near field overflow dredging plume mixing. The focus has been on the most often used dredging vessel: a trailing suction hopper dredger (TSHD). Near field overflow dredging plume mixing is important because it determines the far field...doctoral thesis 2015
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Wei, L. (author), Elsinga, G.E. (author), Brethouwer, G. (author), Schlatter, P. (author), Johansson, A.V. (author)The Reynolds number scaling of flow topology in the eigenframe of the strain-rate tensor is investigated for wall-bounded flows, which is motivated by earlier works showing that such topologies appear to be qualitatively universal across turbulent flows. The databases used in the current study are from direct numerical simulations (DNS) of fully...journal article 2014
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Belt, R.J. (author), Daalmans, A.C.L.M. (author), Portela, L.M. (author)In fully developed single-phase turbulent flow in straight pipes, it is known that mean motions can occur in the plane of the pipe cross-section, when the cross-section is non-circular, or when the wall roughness is non-uniform around the circumference of a circular pipe. This phenomenon is known as secondary flow of the second kind and is...journal article 2012
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Nabi, M. (author)Alluvial open channel beds often exhibit statistically periodic irregularities, known as dunes. Dunes have considerable effects on sediment transport and flow resistance. When growing during a flood, the dunes create more resistance and flood levels may rise significantly. Accurate prediction of dune properties therefore contributes to effective...doctoral thesis 2012
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Hoan, N.T. (author)Despite the fact that many studies on the stability of stones in bed protections under flowing water have been conducted, our knowledge is still far from advanced and reliable. Issues like how to quantify the hydraulic loads exerted on the stones on a bed and the associated stability of the stones are still central and most challenging in stone...doctoral thesis 2008