Maritime Research Institute Netherlands

About: Maritime Research Institute Netherlands is a nonprofit organization based out in Wageningen, Netherlands. It is known for research contribution in the topics: Turbulence & Computational fluid dynamics. The organization has 200 authors who have published 279 publications receiving 4382 citations. The organization is also known as: MARIN.

Variability in Encountered Waves During Deterministically Repeated Seakeeping Tests at Forward Speed

Abstract: Numerical seakeeping codes for ships at forward speed in waves are often validated or tuned based on experiments, which makes knowledge about the experimental variability essential. This variability was evaluated using repeat tests during a state-of-the-art seakeeping campaign. A steep wave condition over the longitudinal basin axis (waveA) and a less steep oblique wave condition (waveB) were studied. Overall similarity as well as individual crest height, steepnesses and timing variability are discussed, because ship response is not equally sensitive for every point in the wave time series. The variability of the measured incoming wave crests and their timing increases with distance from the wave generator for waveA. The crest height variability for waveB is lower and more constant over the basin length (because the propagation distance to the model is constant in oblique waves and wave breaking is less likely). It was shown that only a small part of the variability close to the wave generator is caused by ‘input’ uncertainties such as the accuracy of the wave generator flap motions, measurement carriage position, their synchronisation and measurement accuracy. The rest of the variability is caused by wave and basin effects, such as wave breaking instabilities and small residual wave-induced currents from previous tests. The latter depend on previous wave conditions, which requires further study. Further work on the influence of the wave variability on the variability of ship motions, relative wave elevation along a ship and impact loads on deck of a ship at forward speed will be presented in a next publication.

Experimental and numerical investigation into the effect of Vortex induced vibrations on the motions and loads on circular cylinders in tandem.

Abstract: In this paper a study of the flow around fixed mounted cylinders will be presented. The aim of the study is to set up a method for the computation of the flow around a bundle of flexible cylinders. The flow is assumed to be two-dimensional. The Reynolds number of the flow ranges from 20,000 to 550,000. The calculations for the flow around the fixed circular cylinder were based on commercial available CFD codes such as STAR-CD and CFX 4.2. For the validation of the CFD codes for this application model test experiments were performed on fixed and flexible mounted cylinders. The cylinders were mounted as single cylinder or in pairs. The model test experiments consisted of force measurements in stationary flow as well as detailed Particle Image Velocimetry measurements.