scispace - formally typeset
Search or ask a question
Author

Bas Buchner

Bio: Bas Buchner is an academic researcher from Maritime Research Institute Netherlands. The author has contributed to research in topics: Volume of fluid method & Free surface. The author has an hindex of 13, co-authored 33 publications receiving 1009 citations.

Papers
More filters
Journal ArticleDOI
TL;DR: In this paper, the authors considered some aspects of water impact and green water loading by numerically investigating a dambreak problem and water entry problems, based on the Navier-Stokes equations that describe the flow of a viscous fluid.

618 citations

01 Jan 2001
TL;DR: In this article, a numerical time domain simulation model has been developed for the prediction of the hydrodynamic response of an LNG FPSO with an alongside moored LNG carrier.
Abstract: A numerical time domain simulation model has been developed for the prediction of the hydrodynamic response of an LNG FPSO with an alongside moored LNG carrier. The model has been validated using the findings of dedicated basin model tests. The hydrodynamic response of two bodies in clo se proximity is a complex hydrodynamic interaction problem. Three influencing factors showed to play an important role on the quality of the results: - the use of a free surface lid in the multiple-body diffraction analysis for accurate calculation of the drift forces; - the use of accurate input data on relative viscous damping in the horizontal plane for the correct prediction of the low frequency motion response, and - the use of the complete matrix of retardation functions for the correct prediction of the heave and pitch motions.

107 citations

01 Jan 1999
TL;DR: In this article, the problem of green water loading on the foredeck of a ship is discussed and a comparison is made with experimental results, and forces on different structures placed on the deck are compared and analyzed.
Abstract: Simulating viscous flows with a free surface causes special difficulties, since its position will change continuously. Therefore, besides solving the Navier-Stokes equations, the position of the free surface must be determined every time step. In the present method, the Navier-Stokes equations are solved on a three-dimensional Cartesian grid. A Volume-of-Fluid function is used for the position of the fluid. Since the method is able to handle arbitrary forms of the geometry, many types of industrial flow problems can be simulated. In this paper the problem of green water loading on the foredeck of a ship is discussed and a comparison is made with experimental results. Waterheights, pressures and water contours are produced and compared with model tests. Also forces on different structures placed on the deck are compared and analyzed.

51 citations

Journal ArticleDOI
TL;DR: In this paper, an experimental program was performed on a specific bow shape to determine the probability of wave impact and determining the position of impact on an FPSO (floating production storage and offloading platform) bow geometry.
Abstract: This work aims at characterizing the probability of wave impact and determining the position of impact on an FPSO (floating production storage and offloading platform) bow geometry. In order to determine the instants when impact occurs, an experimental program was performed on a specific bow shape. The bow was instrumented with pressure transducers and the test program, also making use of video recordings, was designed such that it was possible to determine the correlation between undisturbed wave shape and the impact pressure time traces. It has been found that the wave impact at the bow is highly correlated with the local wave steepness, which for very high waves has at least second-order effects. A comparison between the probability distributions of local wave steepness of the experimental undisturbed wave time trace and numerical simulations of second-order wave theory is provided and it confirmed that the latter is very adequate for calculations. The experimental results were further used to determine how the probability of impact varies with free surface vertical velocity. It was found that the significant wave height of the sea state itself does not have significant influence on the result and a regression model was derived for the bow type in the experiments. The proposed model for determining the probability of having an impact is based on combining distributions, adjusted a priori to the numerically generated second-order free surface vertical velocity, and the experimental probability of impact of a known certain seastate and free surface velocity. The analytical description makes it fast and easy to expand to other cases of interest and some example calculations are shown to demonstrate the relative ease of the procedure proposed. The position of the impact is determined by the nonlinear wave crests and the ship motions. The ship motions can be determined based on a linear response to the nonlinear waves considered.

26 citations

Proceedings ArticleDOI
31 Oct 2011
TL;DR: In this article, the effects of operational loads and wind loads on offshore monopile wind turbines are well understood, however, the water depth is such that breaking or near-breaking waves will occur causing impulsive excitation of the monopile and consequently considerable stresses and displacements in the turbine, tower and turbine.
Abstract: The effects of operational loads and wind loads on offshore monopile wind turbines are well understood. For most sites, however, the water depth is such that breaking or near-breaking waves will occur causing impulsive excitation of the monopile and consequently considerable stresses and displacements in the monopile, tower and turbine. To investigate this, pilot model tests were conducted with a special model of an offshore wind turbine with realistic flexibility tested in (extreme) waves. This flexibility was considered to be necessary for two reasons: the impulsive loading of extreme waves is very complex and there can be an interaction between this excitation and the dynamic response of the foundation and tower. The tests confirmed the importance of the topic of breaking waves: horizontal accelerations of more than 0.5g were recorded at nacelle level in extreme cases.© 2011 ASME

24 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: In this paper, the authors considered some aspects of water impact and green water loading by numerically investigating a dambreak problem and water entry problems, based on the Navier-Stokes equations that describe the flow of a viscous fluid.

618 citations

Journal ArticleDOI
TL;DR: In this article, a smoothed particle hydrodynamics model with numerical diffusive terms is used to analyze violent water flows and boundary conditions on solid surfaces of arbitrary shape are enforced with a new technique based on fixed ghost particles.

535 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed modified MPS methods for the prediction of wave impact pressure on a coastal structure by introducing new formulations for the pressure gradient and a new formulation of the source term of the Poisson Pressure Equation (PPE).

288 citations

Journal ArticleDOI
TL;DR: In this paper, the authors conduct experimental measurements on a dam break flow over a horizontal dry bed in order to provide a detailed insight, with emphasis on the pressure loads, into the dynamics of the dam break wave impacting a vertical wall downstream the dam.

236 citations

Journal ArticleDOI
13 Jun 2011-PLOS ONE
TL;DR: Both the achieved speed-ups and the quantitative agreement with experiments suggest that CUDA-based GPU programming can be used in SPH methods with efficiency and reliability.
Abstract: Smoothed Particle Hydrodynamics (SPH) is a numerical method commonly used in Computational Fluid Dynamics (CFD) to simulate complex free-surface flows. Simulations with this mesh-free particle method far exceed the capacity of a single processor. In this paper, as part of a dual-functioning code for either central processing units (CPUs) or Graphics Processor Units (GPUs), a parallelisation using GPUs is presented. The GPU parallelisation technique uses the Compute Unified Device Architecture (CUDA) of nVidia devices. Simulations with more than one million particles on a single GPU card exhibit speedups of up to two orders of magnitude over using a single-core CPU. It is demonstrated that the code achieves different speedups with different CUDA-enabled GPUs. The numerical behaviour of the SPH code is validated with a standard benchmark test case of dam break flow impacting on an obstacle where good agreement with the experimental results is observed. Both the achieved speed-ups and the quantitative agreement with experiments suggest that CUDA-based GPU programming can be used in SPH methods with efficiency and reliability.

219 citations