Wave Radiation by a Floating Body in Water of Finite Depth Using an Exact DtN Boundary Condition

The present paper focuses on the wave radiation by an oscillating body with six degrees of freedom by using the DtN artifi-cial boundary condition.The artificial boundary is usually selected as a circle or spherical surface to solve various types of fields,such as sound waves or electromagnetic waves,provided that the considered domain is infinite or unbounded in all directions.However,the substantial wave motion is considered in water of finite depth,that is,the fluid domain is bounded vertically but unbounded horizon-tally.Thus,the DtN boundary condition is given on an artificial cylindrical surface,which divides the water domain into an interior and exterior region.The boundary integral equation is adopted to implement the present model.In the case of a floating cylinder,the results of hydrodynamic coefficients of a chamfer box are discussed.

Wave Radiation and Diffraction by A Two-Dimensional Floating Body with An Opening Near A Side Wall

The radiation and diffraction problem of a two-dimensional rectangular body with an opening floating on a semi- infinite fluid domain of finite water depth is analysed based on the linearized velocity potential theory through an analytical solution procedure. The expressions for potentials are obtained by the method of variation separation, in which the unknown coefficients are determined by the boundary condition and matching requirement on the interface. The effects of the position of the hole and the gap between the body and side wall on hydrodynamic characteristics are investigated. Some resonance is observed like piston motion in a moon pool and sloshing in a closed tank because of the existence of restricted fluid domains.

Experimental Study of Nonlinear Behaviors of A Free-Floating Body in Waves

Nonlinear behaviors of a free-floating body in waves were experimentally investigated in the present study. The experiments were carried out for 6 different wave heights and 6 different wave periods to cover a relatively wide range of wave nonlinearities. A charge-coupled device （CCD） camera was used to capture the real-time motion of the floating body. The measurement data show that the sway, heave and roll motions of the floating body are all harmonic oscillations while the equilibrium position of the sway motion drifts in the wave direction. The drift speed is proportional to wave steepness when the size of the floating body is comparable to the wavelength, while it is proportional to the square of wave steepness when the floating body is relatively small. In addition, the drift motion leads to a slightly longer oscillation period of the floating body than the wave period of nonlinear wave and the discrepancy increases with the increment of wave steepness.

Mechanism of floating body effect mitigation via cutting off source injection in a fully-depleted silicon-on-insulator technology

In this paper, the effect of floating body effect （FBE） on a single event transient generation mechanism in fully depleted （FD） silicon-on-insulator （SOI） technology is investigated using three-dimensional technology computer-aided design （3D- TCAD） numerical simulation. The results indicate that the main SET generation mechanism is not carder drift/diffusion but floating body effect （FBE） whether for positive or negative channel metal oxide semiconductor （PMOS or NMOS）. Two stacking layout designs mitigating FBE are investigated as well, and the results indicate that the in-line stacking （IS） layout can mitigate FBE completely and is area penalty saving compared with the conventional stacking layout.

THE SUDDEN STARTING OF A FLOATING BODY IN DEEP WATER

This paper applies Lagrangian method to discuss the sudden starting of a floating hotly in deep water and the analytical'solutions are obtained. It is known from the numerical results that the disturbing domain extends and the dynamic pressure also increases when the breadth of the floating body keeps constant and its depth increases.

FREE-SURFACE WAVES AND FAR WAKES GENERATED BY A FLOATING BODY IN A VISCOUS FLUID

The free-surface waves and the flow field due to a body moving on the surfaceof an incompressible viscous fluid of infinite depth were studied analytically. The floating bodywas modeled as a normal point pressure on the free surface. Based on the Oseen approximation forgoverning equations and the linearity assumption for boundary conditions, the exact solutions inintegral form for the free-surface elevation, the velocities and the pressure were given. Byemploying Lighthill's two-stage scheme, the asymptotic representations in far field for largeReynolds numbers were derived explicitly. The effect of viscosity on the wave profiles was expressedby an exponential decay factor, which removes the singular behavior predicted by the potentialtheory.

Body-contact self-bias effect in partially depleted SOI-CMOS and alternatives to suppress floating body effect

As SOI-CMOS technology nodes reach the tens ofnanometer regime, body-contacts become more and more ineffective to suppress the floating body effect. In this paper, self-bias effect as the cause for this failure is analyzed and discussed in depth with respect to different structures and conditions. Other alternative approaches to suppressing the floating body effect are also introduced and discussed.

Gate-to-body tunneling current model for silicon-on-insulator MOSFETs

A gate-to-body tunneling current model for silicon-on-insulator （SOl） devices is simulated. As verified by the mea- sured data, the model, considering both gate voltage and drain voltage dependence as well as image force-induced barrier low effect, provides a better prediction of the tunneling current and gate-induced floating body effect than the BSIMSOI4 model. A delayed gate-induced floating body effect is also predicted by the model.

半潜船波浪诱导运动与载荷预报数值方法比较研究

Numerical simulation tools based on potential-flow theory and/or Morison’s equation are widely used for predicting the hydrodynamic responses of floating offshore wind platforms.In general,these simplified approaches are used for the analysis under operational conditions,albeit with a carefully selected approach to account for viscous effects.Nevertheless,due to the limit hydrodynamic modelling to linear and weakly nonlinear models,these approaches severely underpredict the low-frequency nonlinear wave loads and dynamic responses of a semisubmersible.They may not capture important nonlinearities in severe sea states.For the prediction of wave-induced motions and loads on a semisubmersible,this work systematically compares a fully nonlinear viscous-flow solver and a hybrid model combining the potential-flow theory with Morison-drag loads in steep waves.Results show that when nonlinear phenomena are not dominant,the results obtained by the hybrid model and the high-fidelity method show reasonable agreement,while larger discrepancies occur for highly nonlinear regular waves.Specifically,regular waves with various steepness over different frequencies are focused in the present study,which supplements the understanding in applicability of these two groups of method.

Experimental Investigation on the Hydrodynamic Performance of A Wave Energy Converter

Wave energy is an important type of marine renewable energy. A wave energy converter （WEC） moored with two floating bodies was developed in the present study. To analyze the dynamic performance of the WEC, an experimental device was designed and tested in a tank. The experiment focused on the factors which impact the motion and energy conversion performance of the WEC. Dynamic performance was evaluated by the relative displacements and velocities of the oscillator and carrier which served as the floating bodies of WEC. Four factors were tested, i.e. wave height, wave period, power take-off （PTO） damping, and mass ratio （RM） of the oscillator and carrier. Experimental results show that these factors greatly affect the energy conversion performance, especially when the wave period matches RM and PTO damping. According to the results, we conclude that： （a） the maximization of the relative displacements and velocities leads to the maximization of the energy conversion efficiency; （b） the larger the wave height, the higher the energy conversion efficiency will be; （c） the relationships of energy conversion efficiency with wave period, PTO damping, and RM are nonlinear, but the maximum efficiency is obtained when these three factors are optimally matched. Experimental results demonstrated that the energy conversion efficiency reached the peak at 28.62% when the wave height was 120 mm, wave period was 1.0 s, RM was 0.21, and the PTO damping was corresponding to the resistance of 100 Ω.

A SPH simulation on large-amplitude sloshing for fluids in a two-dimensional tank

Smoothed particle hydrodynamics（SPH） is a mesh-free adaptive Lagrangian particle method with attractive features for dealing with the free surface flow.This paper applies the SPH method to simulate the large-amplitude lateral sloshing both with and without a floating body,and the vertical parametrically-excited sloshing in a two-dimensional tank.The numerical results show that the SPH approach has an obvious advantage over conventional mesh-based methods in handling nonlinear sloshing problems such as violent fluid-solid interaction,and flow separation and wave-breaking on the free fluid surface.The SPH method provides a new alternative and an effective way to solve these special strong nonlinear sloshing problems.

浮体升沉和纵摇运动对甲板上浪载荷影响数值研究（英文）

In this paper,the influence of heave and pitch motions on green water impact on the deck is numerically investigated.The vessel motions are determined using a potential theory based method and provided as input to finite volume based CFD computations of green water phenomenon.A dynamic mesh approach is adopted to determine instantaneous body positioning in the fluid domain.Detailed validation studies with published experimental results for 2D and 3D fixed vessel cases are initially performed to validate the present numerical approach before studying the moving vessel problem.The results show that inclusion of heave and pitch motion changes the disturbed wave field near the bow which influences the free surface as well as the impact loading due to green water.The effect of wave steepness on green water impact is also investigated and it is seen that the present numerical method is capable of capturing green water load.It is observed that the effects of vessel motions on green water load are not negligible and one should consider this effect too.The incorporation of vessel motions in the vertical plane affects the green water loading on the deck.

Eliminating the floating-body effects in a novel CMOS-compatible thin-SOI LDMOS

A novel CMOS-compatible thin film SOI LDMOS with a novel body contact structure is proposed. It has a Si window and a P-body extended to the substrate through the Si window, thus, the P-body touches the P＋ region to form the body contact. Compared with the conventional floating body SOI LDMOS （FB SOI LDMOS） structure, the new structure increases the off-state BV by 54%, decreases the specific on resistance by 20%, improves the output characteristics significantly, and suppresses the self-heating effect. Furthermore, the advantages of the low leakage current and low output capacitance of SOI devices do not degrade.

Impact of back-gate bias on the hysteresis effect in partially depleted SOI MOSFETs

The hysteresis effect in the output characteristics,originating from the floating body effect,has been measured in partially depleted（PD） silicon-on-insulator（SOI） MOSFETs at different back-gate biases.I D hysteresis has been developed to clarify the hysteresis characteristics.The fabricated devices show the positive and negative peaks in the I D hysteresis.The experimental results show that the I D hysteresis is sensitive to the back gate bias in 0.13-渭m PD SOI MOSFETs and does not vary monotonously with the back-gate bias.Based on the steady-state Shockley-Read-Hall（SRH） recombination theory,we have successfully interpreted the impact of the back-gate bias on the hysteresis effect in PD SOI MOSFETs.

INFLUENCE OF GAPS BETWEEN 3-D MULTIPLE FLOATING STRUCTURES ON WAVE FORCES

In the present investigation, influence of gaps between multiple floating structures on wave forces is examined. Strong and complicate hydrodynamic interactions between the floating bodies are observed and the numerical computations have proved the existence of the sharp peak force response on each floating body at some special resonant wave numbers. The resonant wave number is also proved to be around kL=nπ(n=1, 2, …, ∞) with a corresponding frequency shift. A small yet finite gap width will also give influence on the resonant frequency and resonant amplitude of the wave forces, but when the distance between two aligned box-shaped floating bodies becomes big enough, the hydrodynamic interaction can be neglected. The strong hydrodynamic interaction feature has its own important practical significance for the design of module structures and the links (connection) in the whole floating body system. Moreover, the importance is closely related to the hydro-elasticity analyses of a multiple box-shaped floating body system, in which local loads may be as important as the integrated loads.

A TIME DOMAIN INVESTIGATION ON THE HYDRODYNAMIC RESONANCE PHENOMENA OF 3-D MULTIPLE FLOATING STRUCTURES

A 3-D time domain method is developed to investigate the gap influence on the wave threes for 3-D multiple floating structures. Special hydrodynamic resonance due to small gaps between multiple floating structures on wave forces is examined. Strong and complicate hydrodynamic interactions between the floating bodies are observed and the numerical computations have proved the existence of the sharp peak force response on each floating body at some special resonant wave numbers. By comparison with the results from the frequency domain technique, the results obtained from the time domain method reveal the similar resonant phenomena and hydrodynamic interaction. The resonant wave numbers are also proved around kL-nπ （n = 1,2 ……∞） with a corresponding frequency shift. The strong hydrodynamic interaction feature is practically significant for the design of module structures and the links （connection） in whole the floating body system.

WAVE-CURRENT INTERACTIONS WITH THREE-DIMENSIONAL FLOATING BODIES

A Time-domain Higher-Order Boundary Element Method（THOBEM） is developed for simulating wave-current interactions with 3-D floating bodies.Through a Taylor series expansion and a perturbation procedure,the model is formulated to the first-order in the wave steepness and in the current velocity,respectively.The boundary value problem is decomposed into a steady double-body flow problem and an unsteady wave problem.Higher-order boundary integral equation methods are then used to solve the proposed problems with a fourth-order Runge-Kutta method for the time marching.An artificial damping layer is adopted to dissipate the scattering waves.Different from the other time-domain numerical models,which are often focused on the wave-current interaction with restrained bodies,the present model deals with a floating hemisphere.The numerical results of wave forces,wave run-up and body response are all in a close agreement with those obtained by frequency-domain methods.The proposed numerical model is further applied to investigate wave-current interactions with a floating body of complicated geometry.In this work,the regular and focused wave combined with current interacting with a truss-spar platform is investigated.

LOW FREQUENCY WAVE FORCFES ON TWO DIMENSIONAL FLOATING BODIES

Simulating incident group wave with narrow spectrum by nonlinear slowly modulated Stoking wave train and using Multiple Scales Method.problem of the second-order low frequency diffraction of group waves on a two-di mensionai floating body has been studied.The first-order and second-order low frequency diffraction potentials are derived,which lead to the second-order and third-order low frequency forces respectively.It is shown thai the sec- ond-order low frequency force generated by first-order low frequency diffraction potentials is verticcal to undis- turbed free surface,and is directly proportional to square of envelope amplitude of incident wave and to waterline width of floating body.The horizontal low frequency forces are caused by the second-order low frequency diffrac- tion potential.To determine it only two linear boundary value problems are necessary to be solved.

32nd International Workshop on Water Waves and Floating Bodies(IWWWFB2017)

The Thirty-Second Workshop on Water Waves and Floating Bodies was held in Dalian from April23-26,2017,and hosted by State Key Laboratory of Coastal and Offshore Engineering,Dalian University of Technology（DUT）.IWWWFB2017 attracts over90 participants from 17 countries,in which 65participants from abroad.

Analysis on Deepwater Mooring System of Sandglass-Type FDPSO

In order to solve the performance limitations of traditional ship-type and cylindrical FDPSO(floating drilling production, storage and offloading unit), we present a new FDPSO with a sandglass-type floating body.Based on the hydrodynamic performance of the newly developed floating model, a suitable analysis method for its deepwater mooring system has been proposed. Furthermore, by studying the effects of different mooring parameters on the motion performance of FDPSO, we achieve some useful conclusions and principles to design the mooring scheme in deep sea which has been validated to satisfy the Det Norshke Veritas(DNV) requirements.The study of this paper is expected to provide a reasonable and feasible reference and design solution for the deep sea positions of the new sandglass-type FDPSO.