Searched for: subject:"turbulence"
(1 - 20 of 426)

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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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Pestana, T. (author)
Using direct numerical simulations, this thesis studies primarily fundamental aspects of homogeneous rotating turbulence. Within this context, we first investigate the transition from a split to a forward kinetic energy cascade system with a parametric study covering large aspect ratio domains, which are in the direction of rotation up to 340...
doctoral thesis 2020
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Chandramouli, P. (author), Memin, Etienne (author), Heitz, Dominique (author)
We present a variational assimilation technique (4D-Var) to reconstruct time resolved incompressible turbulent flows from measurements on two orthogonal 2D planes. The proposed technique incorporates an error term associated to the flow dynamics. It is therefore a compromise between a strong constraint assimilation procedure (for which the...
journal article 2020
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Broekema, Y.B. (author)
The Eastern Scheldt storm surge barrier is an icon of Dutch hydraulic engineering. Downstream of the barrier, large local erosion pits (scour holes) have formed adjacent to the applied bed protection after its construction. It was expected during the design phase that these would develop, but both the magnitude of the scour hole depth as well as...
doctoral thesis 2020
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Abelmann, Leon (author), Hageman, Tijmen (author), Löthman, Per (author), Mastrangeli, M. (author), Elwenspoek, Miko (author)
Interaction between dipolar forces, such as permanent magnets, generally leads to the formation of one-dimensional chains and rings. We investigated whether it was possible to let dipoles self-assemble into three-dimensional structures by encapsulating them in a shell with a specific shape. We found that the condition for self-assembly of a...
journal article 2020
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Kaandorp, Mikael L.A. (author), Dwight, R.P. (author)
A novel machine learning algorithm is presented, serving as a data-driven turbulence modeling tool for Reynolds Averaged Navier-Stokes (RANS) simulations. This machine learning algorithm, called the Tensor Basis Random Forest (TBRF), is used to predict the Reynolds-stress anisotropy tensor, while guaranteeing Galilean invariance by making use...
journal article 2020
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Löthman, Per A. (author), Hageman, Tijmen A.G. (author), Elwenspoek, Miko C. (author), Krijnen, Gijs J.M. (author), Mastrangeli, M. (author), Manz, Andreas (author), Abelmann, Leon (author)
The extent to which one can use a thermodynamic description of turbulent flow as a source of stochastic kinetic energy for 3D self‐assembly of magnetically interacting macroscopic particles is investigated. It is confirmed that the speed of the objects in the flow field generated in this system obeys the Maxwell–Boltzmann distribution, and their...
journal article 2020
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Prades, Lledó (author), Fabbri, Stefania (author), Dorado, Antonio D. (author), Gamisans, Xavier (author), Stoodley, Paul (author), Picioreanu, C. (author)
Experimental data showed that high-speed microsprays can effectively disrupt biofilms on their support substratum, producing a variety of dynamic reactions such as elongation, displacement, ripple formation, and fluidization. However, the mechanics underlying the impact of high-speed turbulent flows on biofilm structure is complex under such...
journal article 2020
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Martelli, E. (author), Saccoccio, L. (author), Ciottoli, P. P. (author), Tinney, C. E. (author), Baars, Woutijn (author), Bernardini, M. (author)
A delayed detached eddy simulation of an overexpanded nozzle flow with shock-induced separation is carried out at a Reynolds number of, based on nozzle throat diameter and stagnation chamber properties. In this flow, self-sustained shock oscillations induce local unsteady loads on the nozzle wall as well as global off-axis forces. Despite...
journal article 2020
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de Roode, S.R. (author), Siebesma, A.P. (author)
Momentum transport by boundary layer turbulence causes a weak synoptic-scale vertical motion. The classical textbook solution for the strength of this Ekman pumping depends on the curl of the surface momentum flux. A new solution for Ekman pumping is derived in terms of the curl of the geostrophic wind and a term that depends in a nontrivial...
journal article 2020
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Wani, F.M. (author), Shipurkar, U. (author), Dong, J. (author), Polinder, H. (author), Jarquin Laguna, A. (author), Mostafa, Kaswar (author), Lavidas, G. (author)
Thermal cycling is one of the major reasons for failure in power electronic converters. For submerged tidal turbine converters investigating this failure mode is critical in improving the reliability, and minimizing the cost of energy from tidal turbines. This paper considers a submerged tidal turbine converter which is passively cooled by...
journal article 2020
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Flores, Raúl P. (author), Rijnsburger, S. (author), Horner-Devine, Alexander R. (author), Kumar, Nirnimesh (author), Souza, Alejandro J. (author), Pietrzak, J.D. (author)
This study investigates the influence of tidal straining in the generation of turbidity maximum zones (TMZ), which are observed to extend for tens of kilometers along some shallow, open coastal seas. Idealized numerical simulations are conducted to reproduce the cross-shore dynamics and tidal straining in regions of freshwater influence ...
journal article 2020
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Ouro, Pablo (author), Juez, Carmelo (author), Franca, M.J. (author)
Large-Eddy Simulations (LES) are used to investigate the governing processes involved in mass and momentum transfer between the flow in the main channel and symmetrically-distributed lateral bank cavities. In-cavity free-surface velocities, based on laboratory measurements made in an open channel, are used to validate the numerical results. A...
journal article 2020
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Klapwijk, M.D. (author), Lloyd, T. (author), Vaz, G. (author), van Terwisga, T.J.C. (author)
Different variable resolution turbulence modelling approaches (Hybrid, Bridging models and LES) are evaluated for turbulent channel flow at Re<sub>τ</sub>=395, for cases using either streamwise periodic boundary conditions or a synthetic turbulence generator. The effect of iterative, statistical and discretisation errors is investigated. For...
journal article 2020
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Zamponi, R. (author), Satcunanathan, S. (author), Moreau, S. (author), Ragni, D. (author), Meinke, M. (author), Schröder, W. (author), Schram, C. (author)
A possible strategy for the reduction of the aeroacoustic noise generated by turbulence interacting with a wing profile, also referred to as leading-edge noise, is represented by the implementation of a porous medium in the structure of the airfoil. However, the physical mechanisms involved in this noise mitigation technique remain unclear....
journal article 2020
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Tiberga, M. (author), Hennink, A. (author), Kloosterman, J.L. (author), Lathouwers, D. (author)
Accurate methods to solve the Reynolds-Averaged Navier-Stokes (RANS) equations coupled to turbulence models are still of great interest, as this is often the only computationally feasible approach to simulate complex turbulent flows in large engineering applications. In this work, we present a novel discontinuous Galerkin (DG) solver for the...
journal article 2020
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Mukherjee, S. (author)
The mixing of two immiscible fluids, often under turbulent conditions, can lead to the formation of an emulsion, where droplets of one fluid are embedded in another fluid. The occurrence of emulsions is commonplace across industries, ranging from the oil industry to food processing and biotechnology. Why emulsions serve diverse applications, in...
doctoral thesis 2019
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CUI, Guangyao (author), PAN, C. (author), WU, Di (author), Ye, Q. (author), WANG, Jinjun (author)
The characteristics of turbulent boundary layer over streamwise aligned drag reducing riblet surface under zero-pressure gradient are investigated using particle image velocimetry. The formation and distribution of large-scale coherent structures and their effect on momentum partition are analyzed using two-point correlation and probability...
journal article 2019
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Mayer, Jonathan (author), Rubio Carpio, A. (author), Ragni, D. (author)
The present work analyses broadband noise scattering from permeable trailing edges with identical micro-structure but under a change of temperature. Experiments are performed in an anechoic wind tunnel using a NACA0018 airfoil at chord-based Reynolds numbers between 1.88 × 10<sup>5</sup> and 3.14 × 10<sup>5</sup> and no incidence. A...
journal article 2019
Searched for: subject:"turbulence"
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