Searched for: subject%3A%22free%255C-surface%22
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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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Pavilons, David (author)
The most violent breaking waves cause the largest platform forces at sea, however it is unknown which wave in a sea state leads to these forces if run-up is included. Offshore inspection platforms give access to wind turbine monopiles. They are positioned above mean sea level. Wave interaction with monopiles leading to runup causes vertical...
master thesis 2022
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Hillege, Derk (author)
Delft University of Technology has access to a towing tank where a wave maker can generate waves. When generating waves, non-linear start-up effects occur at the start of a wave train which affect the rest of the signal.<br/> The aim of this thesis is to develop a model which can take these effects into account. A numerical modelling approach is...
master thesis 2022
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van Nieuwenhuizen, Christian (author)
The added drag on a buoyant body traveling in a solid-body rotation flow has been rigorously studied over the last century with G.I. Taylor being the first one to describe it in 1922, a hundred years ago. A recent publication by Duinmeijer (2021) investigated the capacity of free-surface vortices to transport solids as a practical application to...
master thesis 2022
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van Meerkerk, M. (author), Poelma, C. (author), Hofland, B. (author), Westerweel, J. (author)
We present an experimental study on the gas flow field development over a plunging breaking wave prior to impact on a vertical wall. The variability of wave impact pressure over repeated measurements is well known (Bagnold, 1939). The formation of instabilities on the wave crest are postulated to be the main source of impact pressure variability...
journal article 2022
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Solergibert I Travé, Oriol (author)
Inspired by the dolphin skin, compliant coatings have been researched as a passive flow control solution to reduce drag. Both successful and drag-increasing experiments can be found in the literature. However, the mechanism is not well understood neither the combination of surface properties and flow conditions that yield a drag reduction. At...
master thesis 2021
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van Meerkerk, M. (author)
The prospect of stricter national and international emission standards for the shipping industry are a driving force in the search for alternative shipping fuels, such as liquefied natural gas (LNG). However, new challenges arise with the widespread use of LNG. For example, there is a desire to use LNG cargo containment...
doctoral thesis 2021
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Duinmeijer, S.P.A. (author), Clemens, F.H.L.R. (author)
Experiments are conducted in a Ø600 mm tank to analyse the 3D motion of buoyant particles in the free-surface vortex flow. The experiments revealed two stages in the particle motion: stage 1 is the helical motion along the vortex air core and stage 2 is the axial motion inside the vortex core. The stage 1 motion is sensitive to the particle’s...
journal article 2021
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Ebrahimi, Amin (author), Kleijn, C.R. (author), Richardson, I.M. (author)
Development, optimisation and qualification of welding and additive manufacturing procedures to date have largely been undertaken on an experimental trial and error basis, which imposes significant costs. Numerical simulations are acknowledged as a promising alternative to experiments, and can improve the understanding of the complex process...
journal article 2021
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Ebrahimi, Amin (author), Kleijn, C.R. (author), Richardson, I.M. (author)
Molten metal melt pools are characterised by highly non-linear responses, which are very sensitive to imposed boundary conditions. Temporal and spatial variations in the energy flux distribution are often neglected in numerical simulations of melt pool behaviour. Additionally, thermo-physical properties of materials are commonly changed to...
journal article 2021
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Cardinale, Lorenzo (author)
Breaking water waves still represent a very active research area, as they are involved in a broad spectrum of situations ranging from safety at sea to climate change. The detailed knowledge of the location of the free surface in case of breaking waves or wave impacts could prevent structural damages, increase the efficiency of ship hulls and...
master thesis 2020
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Duinmeijer, S.P.A. (author)
This is an experimental and theoretical research on the motion of buoyant particles in the flow of a free-surface vortex at moderate to high particle Reynolds numbers.
doctoral thesis 2020
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Lotz, Jacob (author)
Recently the interest in hydrofoil vessels using a fully submerged hydrofoil increased. Hydrofoil vessels experience a resistance hump and possible instabilities during their takeoff of which both are influence by waves. In order to determine the required power during the takeoff to overcome the resistance hump and to investigate whether the...
master thesis 2020
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Wellens, P.R. (author), Borsboom, Mart (author)
The boundaries of numerical domains for free-surface wave simulations with marine structures generate spurious wave reflection if no special measures are taken to prevent it. The common way to prevent reflection is to use dissipation zones at the cost of increased computational effort. On many occasions, the size of the dissipation area is...
journal article 2020
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Sprong, Geert (author)
The bulbous bow is a common feature for large displacement vessels. The purpose of the bulbous bow is to reduce the bow wave, hereby making use of wave cancellation theory. The main drawback of these type of bows is that the drag reduction effect is only present for a limited range of sailing speeds. If the transit velocity is altered, the...
master thesis 2019
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Shen, Zhongwei (author)
This master thesis presents the computation of free-surface flow phenomena with emphasis on ship hydromechanics. We perform a simulation of the heave and the pitch motion of the DTMB 5415M ship moving in head sea. To this purpose we employ an existing Arbitrary-Lagrangian-Eulerian residual-based variational multiscale method (ALE-RBVMS) to...
master thesis 2019
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Akkerman, I. (author), ten Eikelder, M.F.P. (author)
This paper presents a new monolithic free-surface formulation that exhibits correct kinetic and potential energy behavior. We focus in particular on the temporal energy behavior of two-fluids flow with varying densities. Correct energy behavior here means that the actual energy evolution of the numerical solution matches the evolution as...
journal article 2019
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Ebrahimi, Amin (author), Kleijn, C.R. (author), Richardson, I.M. (author)
Heat and fluid flow in low Prandtl number melting pools during laser processing of materials are sensitive to the prescribed boundary conditions, and the responses are highly nonlinear. Previous studies have shown that fluid flow in melt pools with surfactants can be unstable at high Marangoni numbers. In numerical simulations of molten metal...
conference paper 2019
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Krishnan, Vinayak (author)
A novel technique for measuring capillary/gravity waves travelling on air/water interfaces is investigated. The main motivation is to measure the free surface deformations of an air cavity used for air lubrication of ship hulls. Due to limitations in the available techniques, two novel methods are proposed, out of which the Stereo Particle Image...
master thesis 2018
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Meijer, Moos (author)
In numerical methods, correct geometry description and mesh refinement are a challenge. By using a more geometrically based Finite Element Analysis (FEA) type method called ‘Isogeometric Analysis’ (IGA), exact geometry description can be attained, even on coarse meshes. Furthermore, mesh refinement is relatively easy, since no communication with...
master thesis 2018
Searched for: subject%3A%22free%255C-surface%22
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