Hydrodynamic Analysis of Multiple Floating Pontoons With Different Joint Gaps to Waves in Different Water Depth

2017 ◽  
Author(s):  
Xujun Chen ◽  
Yuji Miao ◽  
Xuefeng Tang
Keyword(s):  
Water Depth ◽  
High Frequency ◽  
General Purpose ◽  
Hydrodynamic Properties ◽  
Hydrodynamic Analysis ◽  
Oblique Waves ◽  
Wave Heights ◽  
Floating Bridge ◽  
Significant Wave Heights ◽  
Response Amplitude Operators

The hydrodynamic analysis of a multiple pontoon-type floating bridge (FB) interacting with oblique waves in water of finite arbitrary depth can be performed, at least in principle, using a general-purpose radiation-diffraction code. The fluid is assumed to be inviscid, and the flow can be considered as incompressible and irrotational, and the velocity potentials are calculated by boundary element method. To study the influences of the water depth and the gap between bodies on the hydrodynamic properties of the pontoons, RAOs (Response Amplitude Operators) of modes of each pontoon versus the wave frequencies are calculated and presented. The results show that the RAOs of pitch modes of different pontoons have differences in high frequency in heading waves, and those RAOs differences of heave of different pontoons in heading and oblique waves are small. Furthermore, all the others results nearly match into one. The influences of width of the gap between pontoons to RAOs are small, but the water depth has obvious influence on RAOs. In addition, the motions of FB are simulated and compared in different sea conditions which are represented by the JONSWAP spectrum. The results show that not only the peak wave periods but also the significant wave heights have obvious influences on the motions of the FB.

Hydrodynamic Analysis of Tension Based Tension Leg Platform

2012 ◽  
Author(s):  
D. S. Bhaskara Rao ◽  
R. Panneer Selvam ◽  
Nagan Srinivasan
Keyword(s):  
Water Depth ◽  
Vertical Plane ◽  
Hydrodynamic Analysis ◽  
Response Characteristics ◽  
Deep Waters ◽  
Economical Design ◽  
Motion Responses ◽  
Offshore Industry ◽  
Response Amplitude Operators ◽  
Water Depths

Tension Leg Platforms (TLPs) are one of the best options for offshore industry in deep waters due to proven motion response characteristics. These are water depth sensitive structures and the motion responses in vertical plane motions (heave, roll and pitch) are critical for a TLP. Tension Based TLP (TBTLP) is a new concept and finds application in much deeper waters. A provision of a tension base at mid-depth results in an economical design of TLP. In fact, the TLP installed at a certain depth without any modifications can be made to be deployed in much deeper water depths by means of a tension base. In this paper, the concept of TBTLP is highlighted and hydrodynamic analysis of the chosen platform has been carried out using ANSYS AQWA package. The motion responses in terms of Response Amplitude Operators (RAOs) of TBTLP with one Tension Base in surge, heave and pitch have been obtained and compared with a TLP without a tension base.

scholarly journals Morphodynamic Study of a 2018 Mass-Stranding Event at Punta Umbria Beach (Spain): Effect of Atlantic Storm Emma on Benthic Marine Organisms

2019 ◽  
Vol 7 (10) ◽  
pp. 344
Author(s):  
Juan García-de-Lomas ◽  
Andrés Payo ◽  
Jose A. Cuesta ◽  
Diego Macías
Keyword(s):  
Numerical Model ◽  
Water Depth ◽  
Benthic Organisms ◽  
Beach Profile ◽  
Sipunculus Nudus ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
Low Pressures ◽  
Mass Stranding

Very few mass stranding events of invertebrates have been reported. In this paper, we report a mass stranding of multiple benthic organisms occurred at Punta Umbría beach (S Spain) after the passage of storm Emma (28 February to 5 March 2018). The most abundant organisms were identified, and exceptional meteorological and oceanographic events were analyzed, as a basis to understand the causes of stranding. The morphodynamic changes affecting the beach profile during the storm were inferred using a cross shore depth-integrated and time averaged numerical model (CSHORE). Among the stranded species, decapods (Upogebia spp., Atelecyclus undecimdentatus), sipunculids (Sipunculus nudus), starfish (Astropecten sp.), and sessile tunicates were dominant. Storm Emma involved extreme significant wave heights of up to 7.27 m, low pressures, strong SW winds, precipitations and spring tides that modified the seabed elevation to depth as deep as −10 m. Simulations suggest that benthic organisms living at a water depth between −10 to −0.3 m were buried under a layer of sediment of up to ca. 10 cm deposited during the storm. This burial preceded the transport of intertidal and subtidal benthic organisms to the dry beach, causing their stranding. Impacts on the quality of habitat, biodiversity and the productivity of coastal ecosystems are discussed.

SIMULATION OF NEARSHORE WAVES AND CURRENTS ALONG SALALAH COAST (OMAN) DURING THE TROPICAL CYCLONE ARB01

2017 ◽  
Author(s):  
AbdAlla M. AbdAlla ◽  
AbdAlla M. AbdAlla ◽  
Abkar A. Iraqi ◽  
Abkar A. Iraqi ◽  
Magdy M. Farag ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
Domain Boundary ◽  
Circulation Model ◽  
Shielding Effect ◽  
Strong Current ◽  
Waves And Currents ◽  
Wave Heights ◽  
Nearshore Waves ◽  
Flood Period ◽  
Significant Wave Heights

Sea level and wave data at Salalah coast (Oman) were used to simulate nearshore waves and current during the tropical cyclone ARB01 (9 May2002). STWAVE model (Steady State Spectral Wave) was applied for nearshore wave simulation, while M2D model ((Two-Dimensional Depth Averaged circulation model) was used to simulate nearshore current. The results of simulations (taking into account the mutual effects of both current and waves) showed that: The significant wave heights generally decrease from about 6m at the domain boundary to about 1 m close to the coast. The wave heights during the ebb period were higher than that during the flood period by about 1.5m. Along Salalah coast, higher waves were found along the eastern side of the domain. This is because the shielding effect of breakwater, which protect the western part of the coast from high waves. Relatively Strong current with values up to 1.5 ms-1 were found in the nearshore region during both ebb and flood periods. The M2D model results also showed cyclonic circulations during these periods which help in the renewal of harbor waters. Generally, the model results showed good agreements with observations in the investigated area.

scholarly journals Simulation-Based Power-Loss Optimization of General-Purpose High-Voltage SiC MOSFET Circuit Under High-Frequency Operation

IEEE Access ◽  
2021 ◽  
Vol 9 ◽  
pp. 23786-23794
Author(s):  
Abhishek Kar ◽  
Mitiko Miura-Mattausch ◽  
Mainak Sengupta ◽  
Dondee Navaroo ◽  
Hideyuki Kikuchihara ◽  
...  
Keyword(s):  
High Voltage ◽  
High Frequency ◽  
Power Loss ◽  
General Purpose ◽  
Simulation Based ◽  
High Frequency Operation

An Experimental Study of Shallow Water Wave Statistics on Mild Bed Slopes

2011 ◽  
Author(s):  
Vasiliki Katsardi ◽  
Chris Swan
Keyword(s):  
Water Depth ◽  
Measured Data ◽  
Intermediate Water ◽  
Statistical Distributions ◽  
Spectral Bandwidth ◽  
Peak Period ◽  
Wave Statistics ◽  
Wave Heights ◽  
Bed Slope ◽  
Water Depths

This paper describes a new series of laboratory observations, undertaken in a purpose built wave flume, in which a number of scaled simulations of realistic ocean spectra were allowed to evolve over a range of mild bed slopes. The purpose of the study was to examine the distribution of wave heights and its dependence on the local water depth, d, the local bed slope, m, and the nature of the input spectrum; the latter considering variations in the spectral peak period, Tp, the spectral bandwidth and the wave steepness. The results of the study show that for mild bed slopes the statistical distributions of wave heights are effectively independent of both the bed slope and the spectral bandwidth. However, the peak period plays a very significant role in the sense that it alters the effective water depth. Following detailed comparisons with the measured data, the statistical distributions for wave heights in relatively deep water are found to be in reasonable agreement with the Forristall [1] and Glukhovskii [2] distributions. For intermediate water depths, the Battjes & Groenendijk [3] distribution works very well. However, for the shallowest water depths none of the existing distributions provides good agreement with the measured data; all leading to an over-estimate of the largest wave heights.

Hydrodynamic Properties of an Asymmetric Deepwater Riser Bundle

2006 ◽  
Author(s):  
Charles Zimmermann ◽  
Richard James ◽  
Blaise Seguin ◽  
Mattias Lynch
Keyword(s):  
Cross Section ◽  
Water Depth ◽  
Hydrodynamic Characteristics ◽  
Cfd Analysis ◽  
Effective Solution ◽  
Hydrodynamic Properties ◽  
Global System ◽  
Field Development ◽  
Hydrodynamic Behaviour ◽  
Deepwater Riser

The BP operated Greater Plutonio field development offshore Angola comprises a spread-moored FPSO in 1,300 m water depth, serving as a hub processing the fluids produced from or injected into the subsea wells. The selected riser system is a riser tower tensioned by a steel buoyancy tank at its top end and distributed foam buoyancy along a central structural tubular. The riser bundle is asymmetric in cross-section and this paper presents the work performed to determine the specific hydrodynamic characteristics of the design. Both basin tests and CFD analysis results are presented with discussion on some specific hydrodynamic issues: vortex-induced vibration (VIV) of the global riser tower system, VIV of individual risers, and the dynamic stability of the global system (i.e. galloping). Finally, guidelines for the assessment of the hydrodynamic behaviour of such system geometries are proposed. The results of this paper demonstrate that the Greater Plutonio riser bundle represents an effective solution in term of hydrodynamic behaviour and is not sensitive to VIV fatigue or galloping.

scholarly journals THE PROBABILITY CHARACTERISTICS OP WAVES AND WAVE PRESSURES AT A VERTICAL BREAKWATER

1984 ◽  
Vol 1 (19) ◽  
pp. 50
Author(s):  
Huang Peiji ◽  
Zhao Binglai
Keyword(s):  
Probability Distribution ◽  
High Frequency ◽  
Pressure Field ◽  
Spectral Component ◽  
High Frequency Band ◽  
Wave Pressure ◽  
Spectral Components ◽  
Wave Heights ◽  
Vertical Breakwater ◽  
Equilibrium Range

In this paper, under the condition of waves in front of a breakwater being not broken, studies were made on the characterises of probability distribution of waves and wave pressures, the regularity of the spectral component attenuation with depth and the constitution of the high frequency band of wave pressure spectrum. The distributions of wave heights in front of a vertical breakwater, the range of wave pressure fluctuation at different subsurface levels, and the wave periods have shown that they are practically invariable with depth and can be determined theoretically. The spectral constitution of wave pressure field and the regularity of attenuation of spectral components were analyzed at the vertical breakwater, and a new expression describing the equilibrium range of wave pressure spectrum was obtained.

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