Two-Dimensional Nonlinear Analysis of an Untethered Spherical Buoy Due to Wave Loading

2013 ◽  
Vol 8 (4) ◽  
Author(s):  
Zach Ballard ◽  
Brian P. Mann
Keyword(s):  
Numerical Simulations ◽  
Fluid Motion ◽  
Ocean Waves ◽  
Linear Formulation ◽  
Two Dimensional ◽  
Wave Loading ◽  
Governing Equations ◽  
Nonlinear Formulation ◽  
System Parameters ◽  
Wave Flume

The horizontal and vertical motions of a nonlinear spherical buoy, excited by synthetic ocean waves within a wave flume, is numerically and experimentally investigated. First, fluid motion in the wave tank is described using Airy's theory, and the forces on the buoy are determined using a modified form of Morison's equation. The system is then studied statically in order to determine the effects of varying system parameters. Numerical simulations then use the governing equations to compare predicted motions with experimentally observed behavior. Additionally, a commonly used linear formulation is shown to be insufficient in predicting buoy motion, while the nonlinear formulation presented is shown to be accurate.

Experimental and Numerical Investigations of an Untethered, Nonlinear Spherical Buoy in a Wave Tank

2011 ◽  
Author(s):  
Zach Ballard ◽  
Brian Mann
Keyword(s):  
Numerical Simulations ◽  
Fluid Motion ◽  
Ocean Waves ◽  
Governing Equations ◽  
Wave Tank ◽  
Numerical Investigations ◽  
System Parameters ◽  
Wave Flume ◽  
Observed Behavior

The horizontal and vertical motions of a spherical buoy, excited by synthetic ocean waves within a wave flume, is numerically and experimentally investigated. First, fluid motion in the wave tank is described using Airy’s theory, and the forces on the buoy are determined using a modified form of Morison’s equation. The system is then studied statically in order to determine the effects of varying system parameters. Numerical simulations then use the governing equations to compare predicted motions with experimentally observed behavior.

Regular Wave Experiments for Twin Circular Submerged Floating Tunnel Tethered to Sea Bottom

2017 ◽  
Author(s):  
Sang-Ho Oh ◽  
Woo Sun Park
Keyword(s):  
Hydrodynamic Performance ◽  
Hydrodynamic Characteristics ◽  
Two Dimensional ◽  
Wave Loading ◽  
Regular Waves ◽  
Wave Flume ◽  
Sea Bottom ◽  
Physical Experiments ◽  
Tensile Forces ◽  
Submerged Floating Tunnel

Assessment of hydrodynamic performance of submerged floating tunnel (SFT) under wave loading is one of important factor in the design of the structure. In this study, physical experiments were conducted in a two-dimensional wave flume to investigate hydrodynamic characteristics of a twin circular SFT model under the action of regular waves having different heights and periods. Five different configurations of the twin SFT model was tested in the experiment. The experimental results showed that the three-degree motions of the twin SFT and the associated tensile forces on the tension legs greatly vary with the configurations of the model. It was found that the CD0 configurations are most adequate for satisfactorily restricting the horizontal and vertical motions of the SFT model.

A Two-Dimensional Numerical Wave Flume—Part 1: Nonlinear Wave Generation, Propagation, and Absorption

2001 ◽  
Vol 123 (2) ◽  
pp. 70-75 ◽  
Author(s):  
S. F. Baudic ◽  
A. N. Williams ◽  
A. Kareem
Keyword(s):  
Numerical Model ◽  
Fluid Motion ◽  
Radiation Condition ◽  
Wave Theory ◽  
Published Data ◽  
Computational Domain ◽  
Two Dimensional ◽  
Time Step ◽  
Numerical Wave Flume ◽  
Wave Flume

A numerical model is developed to simulate fully nonlinear transient waves in a semi-infinite, two-dimensional wave tank. A mixed Eulerian-Lagrangian formulation is adopted and a high-order boundary element method is used to solve for the fluid motion at each time step. Input wave characteristics are specified at the upstream boundary of the computational domain using an appropriate wave theory. At the downstream boundary, a damping region is used in conjunction with a radiation condition to prevent wave reflections back into the computational domain. The convergence characteristics of the numerical model are studied and the numerical results are validated through a comparison with previous published data.

Maximum Crest Heights Over an Area and the Air Gap Problem

2006 ◽  
Author(s):  
George Z. Forristall
Keyword(s):  
Numerical Simulations ◽  
Single Point ◽  
Ocean Waves ◽  
The Other ◽  
Wave Crest ◽  
Two Dimensional ◽  
Extreme Wave ◽  
Small Areas ◽  
Dimensional Version ◽  
Crest Height

Ocean waves are dispersive and directionally spread, changing size and shape as they propagate. Therefore the maximum crest height over an area in a given length of time will be larger than the maximum crest at a single point. Extreme crest heights are usually calculated from single point statistics, but the designer of a platform is really interested in the probability of a wave crest reaching any part of the deck area. Statistics for the maximum crest over an area have been developed using a combination of analytic theory and numerical simulations. The resulting crest heights are significantly higher than given by point statistics even for relatively small areas. On the other hand, only a small fraction of the deck may be inundated. That fraction can be estimated by a applying a two dimensional version of the NewWave method that finds the most probable shape of an extreme wave.

scholarly journals Influence of a Standing Wave Flow-Field on the Dynamics of a Spray Diffusion Flame

Fluids ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 27
Author(s):  
J. Barry Greenberg ◽  
David Katoshevski
Keyword(s):  
Liquid Phase ◽  
Flow Field ◽  
Standing Wave ◽  
Diffusion Flame ◽  
Stokes Number ◽  
Flame Height ◽  
Wave Flow ◽  
Two Dimensional ◽  
Governing Equations ◽  
First Time

A theoretical investigation of the influence of a standing wave flow-field on the dynamics of a laminar two-dimensional spray diffusion flame is presented for the first time. The mathematical analysis permits mild slip between the droplets and their host surroundings. For the liquid phase, the use of a small Stokes number as the perturbation parameater enables a solution of the governing equations to be developed. Influence of the standing wave flow-field on droplet grouping is described by a specially constructed modification of the vaporization Damkohler number. Instantaneous flame front shapes are found via a solution for the usual Schwab–Zeldovitch parameter. Numerical results obtained from the analytical solution uncover the strong bearing that droplet grouping, induced by the standing wave flow-field, can have on flame height, shape, and type (over- or under-ventilated) and on the existence of multiple flame fronts.

scholarly journals Towards explicit regulating-ion-transport: nanochannels with only function-elements at outer-surface

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Qun Ma ◽  
Yu Li ◽  
Rongsheng Wang ◽  
Hongquan Xu ◽  
Qiujiao Du ◽  
...  
Keyword(s):  
Ion Transport ◽  
Numerical Simulations ◽  
Power Density ◽  
Outer Surface ◽  
Internal Resistance ◽  
Porous Membranes ◽  
Two Dimensional ◽  
Ionic Selectivity ◽  
Key Features ◽  
Energy Conversion Devices

AbstractFunction elements (FE) are vital components of nanochannel-systems for artificially regulating ion transport. Conventionally, the FE at inner wall (FEIW) of nanochannel−systems are of concern owing to their recognized effect on the compression of ionic passageways. However, their properties are inexplicit or generally presumed from the properties of the FE at outer surface (FEOS), which will bring potential errors. Here, we show that the FEOS independently regulate ion transport in a nanochannel−system without FEIW. The numerical simulations, assigned the measured parameters of FEOS to the Poisson and Nernst-Planck (PNP) equations, are well fitted with the experiments, indicating the generally explicit regulating-ion-transport accomplished by FEOS without FEIW. Meanwhile, the FEOS fulfill the key features of the pervious nanochannel systems on regulating-ion-transport in osmotic energy conversion devices and biosensors, and show advantages to (1) promote power density through concentrating FE at outer surface, bringing increase of ionic selectivity but no obvious change in internal resistance; (2) accommodate probes or targets with size beyond the diameter of nanochannels. Nanochannel-systems with only FEOS of explicit properties provide a quantitative platform for studying substrate transport phenomena through nanoconfined space, including nanopores, nanochannels, nanopipettes, porous membranes and two-dimensional channels.

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