Attenuation of Groundwater Flow Due to Irregular Waves in Permeable Sea Bottom

2014 ◽  
pp. 109-125 ◽  
Author(s):  
Anna Przyborska
Keyword(s):  
Groundwater Flow ◽  
Irregular Waves ◽  
Sea Bottom

Hydrodynamic Forces on Pipelines: Model Tests

1992 ◽  
Vol 114 (4) ◽  
pp. 231-241 ◽  
Author(s):  
M. B. Bryndum ◽  
V. Jacobsen ◽  
D. T. Tsahalis
Keyword(s):  
Cross Flow ◽  
Hydrodynamic Forces ◽  
Irregular Waves ◽  
Regular Waves ◽  
Force Coefficients ◽  
Steady Current ◽  
Sea Bottom ◽  
Least Squares Fit ◽  
Wide Range ◽  
Flow Directions

An extensive model test program on the hydrodynamic forces on a submarine pipeline resting on the sea bottom and exposed to steady current, regular waves, combined steady current and regular waves, irregular waves, and combined steady current and irregular waves has been performed. The hydrodynamic forces in both the in-line and the cross-flow directions have been analyzed using three different methods, i.e., least-squares-fit analysis based on Morison-type equations, Fourier analysis, and maximum force analysis. The force coefficients associated with each method have been determined for a wide range of environmental conditions. The results of the tests are presented in terms of the calculated force coefficients and their dependence on various nondimensional parameters is discussed. Furthermore, comparisons with other test data are presented.

Nonlinear Dynamics of a Floating Wave Energy Converter Reacting Against the Sea Bottom Through a Tight Mooring Cable

2010 ◽  
Author(s):  
Pedro C. Vicente ◽  
Anto´nio F. O. Falca˜o ◽  
Paulo A. P. Justino
Keyword(s):  
Wave Energy ◽  
Time Domain Analysis ◽  
Irregular Waves ◽  
Western Coast ◽  
State University ◽  
Restoring Force ◽  
Wave Energy Converters ◽  
Sea Bottom ◽  
Mooring Cable ◽  
Offshore Wave

Tightly moored single-body floating devices are an important class of offshore wave energy converters. Examples are the devices under development at the University of Uppsala, Sweden, and Oregon State University, USA, prototypes of which were recently tested off the western coast of Sweden and off the Oregon coast, respectively. These devices are equipped with a linear electrical generator. The mooring system consists of a cable that is kept tight by a spring or equivalent device. This cable also prevents the buoy from drifting away by providing a horizontal restoring force. The horizontal and (to a lesser extent) the vertical restoring force are nonlinear functions of the vertical and horizontal displacements of the buoy, which makes the system a nonlinear one (even if the spring and damper are linear), whose modelling requires a time-domain analysis. Such an analysis is presented, preceded by a simpler frequency-domain approach. Numerical results (motions and absorbed power) are shown for a system consisting of a hemispherical buoy in regular and irregular waves, a tight mooring cable and a power take-off system consisting of a linear spring and a linear damper.

Bulk drag coefficient of a subaquatic vegetation subjected to irregular waves: Influence of Reynolds and Keulegan-Carpenter numbers

2020 ◽  
pp. 34-42
Author(s):  
Thibault Chastel ◽  
Kevin Botten ◽  
Nathalie Durand ◽  
Nicole Goutal
Keyword(s):  
Drag Coefficient ◽  
Wave Height ◽  
Wave Attenuation ◽  
Empirical Relationship ◽  
Breaking Waves ◽  
Irregular Waves ◽  
Geometrical Parameters ◽  
Flume Experiments ◽  
Seagrass Meadows ◽  
Artificial Vegetation

Seagrass meadows are essential for protection of coastal erosion by damping wave and stabilizing the seabed. Seagrass are considered as a source of water resistance which modifies strongly the wave dynamics. As a part of EDF R & D seagrass restoration project in the Berre lagoon, we quantify the wave attenuation due to artificial vegetation distributed in a flume. Experiments have been conducted at Saint-Venant Hydraulics Laboratory wave flume (Chatou, France). We measure the wave damping with 13 resistive waves gauges along a distance L = 22.5 m for the “low” density and L = 12.15 m for the “high” density of vegetation mimics. A JONSWAP spectrum is used for the generation of irregular waves with significant wave height Hs ranging from 0.10 to 0.23 m and peak period Tp ranging from 1 to 3 s. Artificial vegetation is a model of Posidonia oceanica seagrass species represented by slightly flexible polypropylene shoots with 8 artificial leaves of 0.28 and 0.16 m height. Different hydrodynamics conditions (Hs, Tp, water depth hw) and geometrical parameters (submergence ratio α, shoot density N) have been tested to see their influence on wave attenuation. For a high submergence ratio (typically 0.7), the wave attenuation can reach 67% of the incident wave height whereas for a low submergence ratio (< 0.2) the wave attenuation is negligible. From each experiment, a bulk drag coefficient has been extracted following the energy dissipation model for irregular non-breaking waves developed by Mendez and Losada (2004). This model, based on the assumption that the energy loss over the species meadow is essentially due to the drag force, takes into account both wave and vegetation parameter. Finally, we found an empirical relationship for Cd depending on 2 dimensionless parameters: the Reynolds and Keulegan-Carpenter numbers. These relationships are compared with other similar studies.

Investigations on Orbital Velocities and Pressures in Irregular Waves

1982 ◽  
Author(s):  
K. -F. Daemrick ◽  
W. -D. Eggert ◽  
H. Cordes
Keyword(s):  
Irregular Waves

Numerical modeling of regional groundwater flow in the Adda-Ticino Basin: advances and new results

2016 ◽  
Vol 41 ◽  
pp. 10-13 ◽  
Author(s):  
Luca Alberti ◽  
Martino Cantone ◽  
Silvia Lombi ◽  
Alessandra Piana
Keyword(s):  
Numerical Modeling ◽  
Groundwater Flow ◽  
Regional Groundwater

Groundwater flow modeling to support water management scenarios – the Bekaa Valley, Lebanon

2016 ◽  
Vol 39 ◽  
pp. 85-88
Author(s):  
Giovanni Formentin ◽  
Mauro Consonni ◽  
Simone Sala ◽  
Vincenzo Francani
Keyword(s):  
Water Management ◽  
Groundwater Flow ◽  
Flow Modeling ◽  
Groundwater Flow Modeling ◽  
Management Scenarios

Remote sea bottom sounding by hydroacoustic systems with complex signals

2009 ◽  
Vol 179 (2) ◽  
pp. 218
Author(s):  
V.I. Kaevitser ◽  
V.M. Razmanov
Keyword(s):  
Complex Signals ◽  
Sea Bottom

On the Effect of the Bucket Attachment Systems on the Bucket Behavior on Sea Bottom

1975 ◽  
Vol 91 (1054) ◽  
pp. 753-758 ◽  
Author(s):  
Norio YAMAKADO ◽  
Keiji HANDA ◽  
Yukinobu MIYASHITA
Keyword(s):  
Sea Bottom

TEMPERATURE VARIABILITY AT SENUNU BAY, WEST SUMBAWA

2013 ◽  
Vol 5 (2) ◽  
Author(s):  
Syamsul Hidayat ◽  
Mulia Purba ◽  
Jorina Waworuntu
Keyword(s):  
Layer Thickness ◽  
Mixed Layer ◽  
Cross Correlation ◽  
Sea Surface ◽  
Thermocline Depth ◽  
Kelvin Wave ◽  
The West ◽  
Sea Bottom ◽  
Annual Period ◽  
Regional Processes

The purposes of this study were to determine the variability of temperature and its relation to regional processes in the Senunu Bay. The result showed clear vertical stratifications i.e., mixed layer thickness about 39-119 m with isotherm of 27°C, thermocline layer thickness about 83-204 m with isotherm of 14–26°C, and  the deeper layer from the thermocline lower limit to the sea bottom with isotherm <13°C. Temperature and the thickness of each layers varied with season in which during the Northwest Monsoon the temperature was warmer and the mixed layer was thicker than those during Southeast Monsoon. During Southeast Monsoon, the thermocline layer rose  about 24 m. The 2001, 2006, and 2009 (weak La Nina years),  the Indonesia Throughflow (ITF) carried warmer water, deepening thermocline depth and reducing upwelling strength.  In 2003 and 2008 thickening of mixed layer occurred in transition season  was believed  associated with the  arrival of Kelvin Wave from the west. In 2002 and 2004 (weak El Nino period,) ITF carries colder water shallowing thermocline depth and enhancing upwelling strength. In 2007 was believed to be related with positive IODM where the sea surface temperature were decreasing due to intensification of southeast wind which induced strong upwelling. The temperature spectral density of mixed layer and thermocline was influenced by annual, semi-annual, intra-annual and inter-annual period fluctuations. The cross-correlation between wind and temperature showed significant value in the annual period.  Keywords: temperature, thermocline, variability, ENSO, IODM.

Sign in / Sign up

Export Citation Format

Share Document