Hidetaka Houtani

Hidetaka Houtani
The University of Tokyo | Todai · Department of Systems Innovation

PhD

About

31
Publications
3,461
Reads
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222
Citations
Citations since 2017
24 Research Items
192 Citations
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201720182019202020212022202301020304050
201720182019202020212022202301020304050

Publications

Publications (31)
Article
Full-text available
Three models with different footing types were used to clarify the effect of heave plates on the hydrodynamic behavior of the elastic response of a flexible multicolumn floating offshore wind turbine (FOWT). The models were tested under regular waves, whose added mass, damping, and motion response results were compared with numerical simulations by...
Article
Full-text available
This paper aims to investigate the nonlinear motion characteristics of a monocolumn type floater with skirts numerically and experimentally. Wave calibration, free decay, and regular wave tests were simulated using a computational fluid dynamics (CFD) code OpenFOAM. The experiments were carried out in a wave tank to validate the CFD results. First,...
Article
Full-text available
The Akhmediev breather (AB) solution of the nonlinear Schrödinger equation (NLSE) shows that the maximum crest height of modulated wave trains reaches triple the initial amplitude as a consequence of nonlinear long-term evolution. Several fully nonlinear numerical studies have indicated that the amplification can exceed 3, but its physical mechanis...
Preprint
The Akhmediev breather (AB) solution of the nonlinear Schr$\"{o}$dinger equation (NLSE) shows that the maximum crest height of modulated wave trains reaches triple the initial amplitude as a consequence of nonlinear long-term evolution. Several fully nonlinear numerical studies have indicated that the amplification can exceed 3, but its physical me...
Conference Paper
A wave field in a wave basin inevitably has spatial variation due to the wave’s cylindrical propagation property. Therefore, we aimed to develop an optimization method for the control of wave-makers to produce a spatially uniform wave field in a specified test zone inside a wave basin with an arbitrary arrangement of wave-makers. The optimization i...
Article
Full-text available
A tank experiment using a flexible multi-column floating offshore wind turbine (FOWT) model in regular waves was carried out to clarify the floater elastic response and its influence on the floater motion. The model motion response from the experiment was compared with the numerical simulations by NK-UTWind and WAMIT codes. The dynamic elastic defo...
Article
Full-text available
A shallow draft cylindrical barge type floater with footing close to the water surface was experimentally evaluated in waves to investigate non-linear motion characteristics. The floater was designed to be used as an option for FOWT—floating offshore wind turbines. The non-linear mechanism can be promoted due to the viscous force that acts on the f...
Chapter
The structural rules of classification societies typically specify various loads corresponding to the sea states which are expected to be encountered by a ship throughout her service life. Consideration of these loads, particularly those for the most severe sea states expected to be encountered, and their impact on hull design are important factors...
Conference Paper
We experimentally investigated the influence of the geometries of a modulated wave train on the vertical-bending and torsional moments acting on a container ship in bow-quartering sea conditions. We conducted a towing experiment with a hydro-structural container ship model in the Actual Sea Model Basin (ASMB) (80 m deep, 40 m wide, and 4.5 m deep)...
Conference Paper
In this study, the feasibility of Fiber Bragg Gratings (FBG) pressure sensors is verified for hull structural strength evaluation. To investigate the effectiveness of FBG pressure sensors for the strength evaluation, the towing tank test is carried out with a pure hydro-structural (PHS) ship model, which is capable of elastic deformation. FBG press...
Conference Paper
The structural rules of classification societies typically specify various loads corresponding to the most severe sea states which are expected to be encountered by a ship throughout her service life in order to ensure ship structural safety, and these rules also usually define a variety of simplified formulae to aid in the calculation of such load...
Article
Full-text available
A floating offshore wind turbine (FOWT) concept with a guy-wire-supported tower was investigated to obtain motion results in waves considering its elastic model characteristics. The FOWT concept studied aims to reduce the construction costs by using a light-weight structure tensioned with guy wires and a downwind type. Wave tank experiments of an e...
Article
An opposing sea was generated in an experimental wave basin. Here, an opposing sea is defined as a sea in which the wave spectrum has two peaks that are separated almost 180° in direction. Such an opposing sea can be observed, for example, when wind waves coexist in the opposite direction with swells. The opposing sea generation is based on an actu...
Conference Paper
Full-text available
A floating offshore wind turbine (FOWT) concept with a guy wire-supported tower was investigated to obtain results of motion in waves considering its elastic model characteristics. The FOWT concept aims to reduce construction costs by using a light-weight structure tensioned with guy wires and a downwind turbine concept type. A wave tank experiment...
Presentation
Full-text available
A floating offshore wind turbine (FOWT) concept with a guy wire-supported tower was investigated to obtain results of motion in waves considering its elastic model characteristics. The FOWT concept aims to reduce construction costs by using a light-weight structure tensioned with guy wires and a downwind turbine concept type. A wave tank experiment...
Conference Paper
Full-text available
A floating offshore wind turbine (FOWT) concept with a guy wire supported tower was investigated to obtain results on its elastic response characteristics in waves and winds. The concept aim is to reduce the cost of FOWTs by using a lightweight structure tensioned with guy wires and a downwind turbine concept. Thereby, the whole floater is a weathe...
Conference Paper
In a model test aimed at investigating statistically the ship response in an actual sea condition, it is needed that the short-crested irregular waves are generated for a long duration. The characteristics of the wave field should be kept unchanged in time. In this study, the authors have investigated the temporal variation of a short-crested irreg...
Article
The excessive acceleration is one of five stability failure modes for intact stability being discussed at IMO. The trial calculation for Direct Stability Assessment (DSA) and the model test have been carried out to verify two prediction methods of ship motions in the short-crested irregular waves for DSA. The ship motions in the short-crested irreg...
Article
A towing experiment was conducted using a modulated wave train to investigate the vertical bending responses of a hydro-structural container ship model. In the experiment, a spatially periodic modulated wave train, as a model of a freak wave in successive high waves mimicking the so-called three sisters, was generated by the recently established hi...
Article
We herein propose a new design procedure of a flexible container ship model where the vertical bending and torsional vibration modes are similar to its prototype. To achieve similarity in torsional vibration mode shapes, the height of the shear center of the model must be located below the bottom hull, similar to an actual container ship with large...
Article
Full-text available
This paper proposes a design strategy of a hydro-structural model considering the vertical-bending and torsional vibration mode shapes. A ship with large opening decks, such as a container ship, has its shear center below its bottom hull. In the proposed design strategy, such a shear center location is achieved for a ship model by imparting appropr...
Article
A new wave generation method, called HOSM-WG, is presented in this paper. The method utilizes the precomputed spatially periodic wave field based on the higher-order spectral method (HOSM) simulation to calculate the wave-maker signals. The spatially periodic wave fields were reproduced in a rectangular basin with 382 wave makers on the peripheral....
Article
Full-text available
A number of studies on steep nonlinear waves were conducted experimentally with the temporally periodic and spatially evolving (TPSE) wave trains and numerically with the spatially periodic and temporally evolving (SPTE) ones. The present study revealed that, in the vicinity of their maximum crest height, the wave profiles of TPSE and SPTE modulate...
Article
Full-text available
This paper proposes a method to simultaneously measure wave profiles and particle velocity on a wave surface by stereo imaging. About 100 markers are used as floats in the measurement. The motion of the markers is tracked by stereo cameras. From the position of the markers, the wave profile and the particle velocity on the wave surface are estimate...
Conference Paper
A method to produce freak waves with arbitrary spectrum in a fully directional wave basin is presented here. This is an extension of Waseda, Houtani and Tanizawa at OMAE 2013[1], which used “HOSM-WG” based on the higher-order spectral method (HOSM). We used the following three methods to improve the HOSM-WG in [1]: “separation of free waves from bo...
Article
Full-text available
Interaction with an opposing current amplifies wave modulation and accelerates nonlinear wave focusing in regular wavepackets. This results in large-amplitude waves, usually known as rogue waves, even if the wave conditions are less prone to extremes. Laboratory experiments in three independent facilities are presented here to assess the role of op...
Conference Paper
The purpose of this study is to investigate ship motions of a small trawler with advanced speed in wash wave. Authors have proposed a reproduction method of wash wave by wave generator. By using the reproduction method of wash wave, the ship motions of the small trawler with an advanced speed in wash wave of a container ship reproduced by wave gene...
Conference Paper
Spatially periodic modulational wave train was generated at the National Maritime Research Institute, Actual Sea Model Basin. The 76 m by 36 m basin of depth 4.5 m is surrounded by 382 paddle type wave generators with wave absorbing capacity. Taking advantage of this unique wave basin, we have compared two generation methods, first controlling the...
Article
Full-text available
We show experimentally that a stable wave propagating into a region characterized by an opposite current may become modulationally unstable. Experiments have been performed in two independent wave tank facilities; both of them are equipped with a wavemaker and a pump for generating a current propagating in the opposite direction with respect to the...
Article
The purpose of the study is to establish a technique for computing wash wave using capturing approach with Reynolds Averaged Navier-Stokes (RANS) Solver and to provide data, which should be input to multi-segmented wave generators for reproducing wash wave in a model basin. The flow solver used in this study is NEPTUNE developed at National Maritim...
Article
Full-text available
The modulational instability or the quasi-resonance is considered to play a pivotal role in the generation of freak waves in the ocean. The steepness and the frequency bandwidth, which are known to govern the initial stability of both regular and irregular wave train, are now used to predict the long-term evolution. In this study we extend the pion...

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