Searched for: subject%3A%22instability%22
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Peng, K. (author)
In the upcoming decades, a substantial growth in the commercial aviation market is anticipated, accompanied by an increasing societal awareness of global warming. This circumstance necessitates a technological development for emission reduction in future transport aircraft. A method for aerodynamic efficiency improvement is the so-called Laminar...
doctoral thesis 2024
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van Winden, Brian (author)
Introduction<br/>Approximately 9 in 1000 children are born with congenital heart disease (CHD), of whom a quarter are classified as critical CHD (CCHD) and require an intervention within their first year. Monitoring these patients in the Paediatric Intensive Care Unit (PICU) is crucial, yet with increasing amounts of data, detecting subtle...
master thesis 2024
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Shajahan, M.T. (author)
Dense suspension flows, both in the natural environment and industrial settings, are complex phenomena with significant implications. From rivers shaping landscapes to industrial processes involving slurry transport, these flows hold a prominent position in numerous sectors. This thesis delves into a specific facet of these intricate flows:...
doctoral thesis 2024
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van de Weijer, Tim (author)
An important challenge in the electrification of aircraft propulsion systems is the design of thermal management systems because of an increased heat load that needs to be dissipated. As an alternative to high-drag external heat exchangers, one can consider surface heat exchangers to dissipate the extra thermal energy. This reduces the size of...
master thesis 2024
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Magherini, A. (author), Yan Toe, C. (author), Stancanelli, L.M. (author), Wüthrich, D. (author), Uijttewaal, W.S.J. (author)
Plastic pollution is a threat for all ecosystems due to its effects on people, animals, and environment (Mai et al., 2020). Rivers are estimated to transport around 0.5 millions tons of plastic per year (Strokal et al., 2023). When plastic enters a river system, it is transported downstream towards the sea but it is also likely to accumulate at...
abstract 2024
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Akrish, G. (author), Reniers, A.J.H.M. (author), Zijlema, Marcel (author), Smit, P.B. (author)
Coastal wave forecasting over large spatial scales is essential for many applications (e.g., coastal safety assessments, coastal management and developments, etc.). This demand explains the necessity for accurate yet effective models. A well-known efficient modelling approach is the quadratic approach (often referred to as frequency-domain...
journal article 2024
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Bugeat, B. (author), Boldini, P.C. (author), Hasan, A.M. (author), Pecnik, Rene (author)
This paper addresses the stability of plane Couette flow in the presence of strong density and viscosity stratifications. It demonstrates the existence of a generalised inflection point that satisfies the generalised Fjørtoft criterion of instability when a minimum of kinematic viscosity is present in the base flow. The characteristic scales...
journal article 2024
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ten Wolde, M.A. (author), Farhadi Machekposhti, D. (author)
Bistable mechanisms are prevalent across a broad spectrum of applications due to their ability to maintain two distinct stable states. Their energy consumption is predominantly confined to the process of state transitions, thereby enhancing their efficiency. However, the transition often requires two distinct digital inputs, implicating the...
journal article 2024
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de Vries, Sietse (author), Schuller, Tomás (author), Galindo-Rosales, Francisco J. (author), Fanzio, P. (author)
Fused Filament Fabrication is an additive manufacturing technique in which molten thermoplastic polymers are extruded through a nozzle. Therefore, the interplay between the viscoelastic nature of the polymer melt, temperature, printing conditions and nozzle shape may lead to inconsistent extrusion. To improve the extrusion control and...
journal article 2024
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Aly, H.A. (author), Nealon, Rebecca (author), Gonzalez, Jean-François (author)
We identify a new dust instability that occurs in warped discs. The instability is caused by the oscillatory gas motions induced by the warp in the bending wave regime. We first demonstrate the instability using a local 1D (vertical) toy model based on the warped shearing box coordinates and investigate the effects of the warp magnitude and...
journal article 2024
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Tambe, S.S. (author), Kato, Kentaro (author), Hussain, Zahir (author)
This paper reports on the efficacy of the Görtler number in scaling the laminar-turbulent boundary-layer transition on rotating cones facing axial inflow. Depending on the half-cone angle and axial flow strength, the competing centrifugal and cross-flow instabilities dominate the transition. Traditionally, the flow is evaluated by using two...
journal article 2024
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Bouwmeesters, Max (author)
Wind turbines experience a wide variety of load cases, both when in operation and when parked. While a turbine in operating conditions often experiences larger loads than in parked conditions, uniquely large inflow angles may occur in parked conditions resulting in less well-understood aeroelastic conditions. Vibrations under these conditions...
master thesis 2023
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Bogaerts, Charlie (author)
This study aims to quantify the aerodynamic behaviour of fixed pitch rotors with a diameter of 12.7 cm in axial descent, and its contribution to the attitude oscillations found for quadcopters under similar flight conditions. Wind tunnel tests are performed with an isolated rotor, as well as a complete quadcopter mounted inside a gimbal that...
master thesis 2023
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Zoppini, G. (author)
The research presented in this thesis focuses on the receptivity to surface roughness of swept wing boundary layers dominated by crossflow instabilities (CFI), providing insights into how surface roughness can be used to passively control the developing instabilities. Discrete roughness elements (DRE) arrays and distributed randomized roughness...
doctoral thesis 2023
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Madhavan, Aravind Krishna (author)
This investigation focuses on the premixed conical flame, a mainstay of combustion diagnostics. While extensive studies have explored high-frequency oscillations in the canonical Bunsen flame, little attention has been given to low-frequency oscillations affecting flame fronts. This thesis aims to explain the origins of these oscillations and...
master thesis 2023
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Formidabile, Martina (author)
TOP contoured nozzles, with large area-ratios, are commonly employed in rocket propulsion systems as they feature an excellent thrust-to-weight ratio. A significant shortcoming to this design is that, during the startup and shutdown transients of a LRE, the internal nozzle flow progresses through a series of overexpanded flow states - Free Shock...
master thesis 2023
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Trotta, Luca (author)
High-frequency combustion instabilities represent the main technical risk faced by design engineers when developing new chemical rocket propulsion systems. Such instabilities are driven by the coupling between the flames’ heat release rate and the combustion chamber’s acoustic field. As such, they can only be assessed during detailed design...
master thesis 2023
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Kamis, Y.E. (author), Prakash, Suriya (author), Breugem, W.P. (author), Eral, H.B. (author)
We experimentally and numerically study the dynamics of a liquid jet issued from a rotating orifice, whose breakup is regulated by a vibrating piezo element. The helical trajectory of the spiralling jet yields fictitious forces varying along the jet whose longitudinal projections stretch and thin the jet, affecting the growth of perturbations....
journal article 2023
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Tang, Tianning (author), Moss, Charlotte (author), Draycott, Samuel (author), Bingham, Harry B. (author), van den Bremer, T.S. (author), Li, Yan (author), Adcock, Thomas A.A. (author)
An increased number of rogue waves, relative to standard distributions, can be induced by unidirectional waves passing over abrupt decreases in water depth. We investigate this phenomenon in a more general setting of multidirectional waves. We examine the influence of the directionality on the occurrence probability of rogue waves using...
journal article 2023
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Pol, J.C. (author), Kindermann, P.E. (author), van der Krogt, M.G. (author), van Bergeijk, Vera M. (author), Remmerswaal, G. (author), Kanning, W. (author), Jonkman, Sebastiaan N. (author), Kok, M. (author)
Structural reliability analysis often considers failure mechanisms as correlated but non-interacting processes. Interacting failure mechanisms affect each others performance, and thereby the system reliability. We describe such interactions in the context of flood defenses, and analyze under which conditions such interactions have a large impact...
journal article 2023
Searched for: subject%3A%22instability%22
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