A BASIC STUDY ON THE MOVEMENT CHARACTERISTICS OF SEDIMENT TRANSPORT BASED ON THE PHYSICAL PARAMETERS OF FORAMINIFERA IN CORAL REEF BEACHES

2021 ◽  
Vol 77 (2) ◽  
pp. I_349-I_354
Author(s):  
Takeru MASUTANI ◽  
Gozo TSUJIMOTO ◽  
Sooyoul KIM
Keyword(s):  
Coral Reef ◽  
Sediment Transport ◽  
Physical Parameters ◽  
Basic Study ◽  
Movement Characteristics

scholarly journals Bedforms in a turbulent stream: ripples, chevrons and antidunes

2011 ◽  
Vol 690 ◽  
pp. 94-128 ◽  
Author(s):  
Bruno Andreotti ◽  
Philippe Claudin ◽  
Olivier Devauchelle ◽  
Orencio Durán ◽  
Antoine Fourrière
Keyword(s):  
Free Surface ◽  
Sediment Transport ◽  
Flow Direction ◽  
Linear Instability ◽  
Physical Parameters ◽  
Flow Depth ◽  
Supercritical Regime ◽  
Free Surface Waves ◽  
Alternate Bars ◽  
Flooding Events

AbstractThe interaction between a turbulent flow and a granular bed via sediment transport produces various bedforms associated with distinct hydrodynamical regimes. In this paper, we compare ripples (downstream-propagating transverse bedforms), chevrons and bars (bedforms inclined with respect to the flow direction) and antidunes (upstream-propagating bedforms), focusing on the mechanisms involved in the early stages of their formation. Performing the linear stability analysis of a flat bed, we study the asymptotic behaviours of the dispersion relation with respect to the physical parameters of the problem. In the subcritical regime (Froude number $\mathscr{F}$ smaller than unity), we show that the same instability produces ripples or chevrons depending on the influence of the free surface. The transition from transverse to inclined bedforms is controlled by the ratio of the saturation length ${L}_{\mathit{sat}} $, which encodes the stabilizing effect of sediment transport, to the flow depth $H$, which determines the hydrodynamical regime. These results suggest that alternate bars form in rivers during flooding events, when suspended load dominates over bedload. In the supercritical regime $\mathscr{F}\gt 1$, the transition from ripples to antidunes is also controlled by the ratio ${L}_{\mathit{sat}} / H$. Antidunes appear around resonant conditions for free surface waves, a situation for which the sediment transport saturation becomes destabilizing. This resonance turns out to be fundamentally different from the inviscid prediction. Their wavelength selected by linear instability mostly scales on the flow depth $H$, which is in agreement with existing experimental data. Our results also predict the emergence, at large Froude numbers, of ‘antichevrons’ or ‘antibars’, i.e. bedforms inclined with respect to the flow and propagating upstream.

scholarly journals Circulation and suspended sediment transport in a coral reef lagoon: The south-west lagoon of New Caledonia

2010 ◽  
Vol 61 (7-12) ◽  
pp. 269-296 ◽  
Author(s):  
S. Ouillon ◽  
P. Douillet ◽  
J.P. Lefebvre ◽  
R. Le Gendre ◽  
A. Jouon ◽  
...  
Keyword(s):  
Coral Reef ◽  
Sediment Transport ◽  
Suspended Sediment ◽  
New Caledonia ◽  
Suspended Sediment Transport ◽  
The South ◽  
Reef Lagoon ◽  
South West ◽  
Coral Reef Lagoon

Sediment transport and mixing depth on a coral reef sand apron

Geomorphology ◽  
2014 ◽  
Vol 222 ◽  
pp. 143-150 ◽  
Author(s):  
Ana Vila-Concejo ◽  
Daniel L. Harris ◽  
Hannah E. Power ◽  
Amelia M. Shannon ◽  
Jody M. Webster
Keyword(s):  
Coral Reef ◽  
Sediment Transport ◽  
Mixing Depth ◽  
Transport And Mixing

scholarly journals Coupled Delft3D-Object Model to Predict Mobility of Munition on Sandy Seafloor

Fluids ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 330
Author(s):  
Peter C. Chu ◽  
Vinicius S. Pessanha ◽  
Chenwu Fan ◽  
Joseph Calantoni
Keyword(s):  
Experimental Data ◽  
Sediment Transport ◽  
Time Series Data ◽  
Major Axis ◽  
Series Data ◽  
Physical Parameters ◽  
Object Model ◽  
Wave Direction ◽  
Rolling Moment ◽  
Object Mobility

The coupled Delft3D-object model has been developed to predict the mobility and burial of objects on sandy seafloors. The Delft3D model is used to predict seabed environmental factors such as currents, waves (peak wave period, significant wave height, wave direction), water level, sediment transport, and seabed change, which are taken as the forcing term to the object model consisting of three components: (a) physical parameters such as diameter, length, mass, and rolling moment; (b) dynamics of the rolling cylinder around its major axis; (c) an empirical sediment scour model with re-exposure parameterization. The model is compared with the observational data collected from a field experiment from 21 April to 13 May 2013 off the coast of Panama City, Florida. The experimental data contain both object mobility using sector scanning sonars and maintenance divers as well as simultaneous environmental time series data of the boundary layer hydrodynamics and sediment transport conditions. Comparison between modeled and observed data clearly shows the model’s capabilities and limitations.

The Contribution of Currents, Sea‐Swell Waves, and Infragravity Waves to Suspended‐Sediment Transport Across a Coral Reef‐Lagoon System

2021 ◽  
Vol 126 (3) ◽  
Author(s):  
Andrew W. M. Pomeroy ◽  
Curt D. Storlazzi ◽  
Kurt J. Rosenberger ◽  
Ryan J. Lowe ◽  
Jeff E. Hansen ◽  
...  
Keyword(s):  
Coral Reef ◽  
Sediment Transport ◽  
Suspended Sediment ◽  
Suspended Sediment Transport ◽  
Infragravity Waves ◽  
Reef Lagoon ◽  
Lagoon System ◽  
Coral Reef Lagoon

Improving shore protection design

1990 ◽  
Vol 17 (2) ◽  
pp. 142-147
Author(s):  
J. William Kamphuis
Keyword(s):  
Sediment Transport ◽  
Key Words ◽  
Physical Parameters ◽  
Shore Protection

The construction of shore protection is expensive, but the alternative of permitting erosion is also expensive. Yet any design of shore protection is based mostly on intuitive concepts. This paper presents an overview of what is lacking in our knowledge, a possible methodology for improving shore protection design and discussions about some of the most important (and often ignored) physical parameters to be considered if shore protection is to perform its task without interfering with the littoral environment. Key words: erosion, groins, seawalls, sediment transport, shore protection.

scholarly journals Coupled Delft3D-Object Model to Predict Mobility and Burial of Munition on Sandy Floor

2021 ◽  
Author(s):  
Peter C. Chu ◽  
Vinicius S. Pessanha ◽  
Chenwu Fan
Keyword(s):  
Sediment Transport ◽  
Time Series Data ◽  
Development Program ◽  
Environmental Research ◽  
Series Data ◽  
Physical Parameters ◽  
Object Model ◽  
Wave Direction ◽  
Peak Period ◽  
Rolling Moment

Coupled Delft3D-object model has been developed to predict object’s mobility and burial on sandy seafloor. The Delft3D model is used to predict seabed environment such as currents, waves (peak period, significant wave height, wave direction), water level, sediment transport, and seabed change, which are taken as the forcing term to the object model consisting of three components: (a) object‘s physical parameters such as diameter, length, mass, and rolling moment, (b) dynamics of rolling cylinder around its major axis, and (c) empirical sediment scour model with re-exposure parameterization. The model is compared with the observational data collected from a field experiment from 21 April to 23 May 2013 off the coast of Panama City, Florida funded by the Department of Defense Strategic Environmental Research and Development Program. The experimental data contain both objects’ mobility using sector scanning and pencil beam sonars and simultaneous environmental time series data of the boundary layer hydrodynamics and sediment transport conditions. Comparison between modeled and observed data clearly show the model capability.

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