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Makaveev, Momchil (author)This project proposes and evaluates a novel concept for an airspeed instrument aimed at small hybrid unmanned aerial vehicles. The working principle is to relate the power spectra of the wall-pressure fluctuations beneath the turbulent boundary layer formed over the vehicle’s body to its airspeed. The instrument consists of two microphones,...master thesis 2023
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Hosseini, A. (author), Hage, Johannes (author), Meijer, Koen (author), Offerman, S.E. (author), Yang, Y. (author)In this paper a CFD analysis of HIsarna off-gas system for post combustion of CO-H2-carbon particle mixture is presented to evaluate the effect of different sub-models and parameters on the accuracy of predictions and simulation time. The effects of different mesh type, mesh grid size, radiation models, turbulent models, kinetic mechanism,...journal article 2023
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Elsinga, G.E. (author), Ishihara, Takashi (author), Hunt, J.C.R. (author)Direct numerical simulations up to Reλ = 1445 show that the scaling exponents for the enstrophy and the dissipation rate extrema are different and depend on the Reynolds number. A similar Reynolds number dependence of the scaling exponents is observed for the moments of the dissipation rate, but not for the moments of the enstrophy. Significant...journal article 2023
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Zamponi, R. (author), Satcunanathan, S. (author), Moreau, S. (author), Meinke, M. (author), Schröder, W. (author), Schram, C. (author)Integrating a porous material into the structure of an aerofoil constitutes a promising passive strategy for mitigating the noise from turbulence–body interactions that has been extensively explored in the past few decades. When a compact permeable body is considered in the aeroacoustic analogy derived by Curle to predict this noise source, a...journal article 2023
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Carrasco Grau, J. (author), van Campenhout, O.W.G. (author), Hartog, F.H. (author), van Nesselrooij, M. (author), Baars, W.J. (author), Schrijer, F.F.J. (author)Chevron-shaped protrusions have been proposed in the literature for turbulent skin friction reduction. However, there is no consensus on the performance of this passive flow control technique; both an increase and a decrease in drag have been observed in previous studies. There is also no experimental evidence to support the working mechanism...journal article 2023
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Pirozzoli, Sergio (author), Modesti, D. (author)We carry out direct numerical simulations (DNS) of turbulent flow and heat transfer in pressure-driven plane channels, by considering cases with heating on both walls, as well as asymmetric heating limited to one of the channel walls. Friction Reynolds numbers up to are considered, and Prandtl numbers from to, the temperature field being...journal article 2023
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Makaveev, M.K. (author), Snellen, M. (author), Smeur, E.J.J. (author)This paper puts forward a novel design for an airspeed instrument aimed at small fixed-wing tail-sitter unmanned aerial vehicles. The working principle is to relate the power spectra of the wall-pressure fluctuations beneath the turbulent boundary layer present over the vehicle’s body in flight to its airspeed. The instrument consists of two...journal article 2023
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Bernardini, Matteo (author), Modesti, D. (author), Salvadore, Francesco (author), Sathyanarayana, Srikanth (author), Della Posta, Giacomo (author), Pirozzoli, Sergio (author)We present STREAmS-2.0, an updated version of the flow solver STREAmS, first introduced in Bernardini et al. (2021) [1]. STREAmS-2.0 has an object-oriented design which separates the physics equations from the specific back-end, making the code more suitable for future expansions, such as porting to novel computing architectures or...journal article 2023
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Dai, Y. (author), Boekee, J. (author), Schilperoort, B. (author), ten Veldhuis, Marie-claire (author), van de Wiel, B.J.H. (author)Wind machines have been increasingly used for frost damage mitigation in the agricultural community. During radiative frost nights, wind machines are used to erode near-surface thermal inversion by air mixing. The underlying mixing processes remain poorly understood. A full picture of warming effects caused by air mixing requires measurements...journal article 2023
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Mulder, G. (author), van Leijen, F.J. (author), Hanssen, R.F. (author)The observed phase in time series of interferometric synthetic aperture radar (InSAR) products is a superposition of various components. Differential topography, line-of-sight displacements, and differential atmospheric delays are the main contributions and need to be disentangled to derive accurate digital elevation model (DEM), deformation,...journal article 2023
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Zou, P. (author), Kim, Taeksang (author), Bricker, J.D. (author), Uijttewaal, W.S.J. (author)The modelling of complex free surface flows is challenging due to the mobility and deformability of the interface and air entrainment characteristics, which are highly affected by turbulence. With the framework of Reynolds averaged Navier–Stokes (RANS) models and the volume of fluid (VOF) method, turbulence quantities at the air–water...journal article 2023
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Diez Sanhueza, R.G. (author), Akkerman, I. (author), Peeters, J.W.R. (author)Turbulent flows past rough surfaces can create substantial energy losses in engineering equipment. During the last decades, developing accurate correlations to predict the thermal and hydrodynamic behavior of rough surfaces has proven to be a difficult challenge. In this work, we investigate the applicability of convolutional neural networks...journal article 2023
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Cimarelli, Andrea (author), Boga, Gabriele (author), Pavan, Anna (author), Costa, Pedro (author), Stalio, Enrico (author)The geometrically complex mechanisms of energy transfer in the compound space of scales and positions of wall turbulent flows are investigated in a temporally evolving boundary layer. The phenomena consist of spatially ascending reverse and forward cascades from the small production scales of the buffer layer to the small dissipative scales...journal article 2023
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Keetels, G.H. (author), Chauchat, Julien (author), Breugem, W.P. (author)Reliable prediction of the erosion rate of sediment beds is important for many applications in coastal and river engineering. Theoretical understanding of empirically derived scaling relations is still lacking. This applies in particular for the scaling anomaly between low and high Shields number conditions. In this work, the erosion process is...journal article 2023
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Spitzer, Stefan H. (author), Askar, Enis (author), Benke, Alexander (author), Cloney, Chris (author), D'Hyon, Sebastian (author), Dufaud, Olivier (author), Dyduch, Zdzislaw (author), Gabel, Dieter (author), Taveau, J.R. (author)There is no applicable existing standard for the determination of safety characteristics for hybrid mixtures. While developing a new standard in a joint research project in Germany first results from parameter studies led to a standard procedure that can be adopted by laboratories that are already testing dusts in the so called 20L-sphere...journal article 2023
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van Campenhout, O.W.G. (author), van Nesselrooij, M. (author), Lin, Y. (author), Casacuberta Puig, J. (author), van Oudheusden, B.W. (author), Hickel, S. (author)Although several previous studies have reported a potential drag-reducing effect of dimpled surfaces in turbulent boundary layers, there is a lack of replicability across experiments performed by different research groups. To contribute to the dialogue, we scrutinize one of the most studied dimple geometries reported in the literature, which...journal article 2023
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Diez Sanhueza, R.G. (author), Smit, S.H.H.J. (author), Peeters, J.W.R. (author), Pecnik, Rene (author)This paper presents a machine learning methodology to improve the predictions of traditional RANS turbulence models in channel flows subject to strong variations in their thermophysical properties. The developed formulation contains several improvements over the existing Field Inversion Machine Learning (FIML) frameworks described in the...journal article 2023
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Noel, L.F.P. (author), Maute, K. (author)Solving conjugate heat transfer design problems is relevant for various engineering applications requiring efficient thermal management. Heat exchange between fluid and solid can be enhanced by optimizing the system layout and the shape of the flow channels. As heat is transferred at fluid/solid interfaces, it is crucial to accurately resolve...journal article 2023
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Fathi, Mohamad (author), Hickel, S. (author), Roekaerts, D.J.E.M. (author)Transcritical fuel sprays form an indispensable part of high-pressure energy-conversion systems. Modeling the complex real-fluid effects in the high-pressure multiphase regime of such sprays accurately, especially the hybrid subcritical-to-supercritical mode of evaporation during mixing fuel and oxidizer, is essential and challenging. This...book chapter 2023
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Korevaar, C.W. (author), Saathof, R. (author), van Abkoude, Tara (author), Doelman, Niek J. (author)Optical feeder links (OFLs) benefit from the vast amount of bandwidth available in the THz-regime of the electromagnetic spectrum, and can be considered as enablers for future terabit-per-second satellite systems. A particular challenge for OFLs is to mitigate the effects of fading, caused by a combination of turbulence-induced scintillation,...conference paper 2023