scholarly journals MODELING SEDIMENTATION AT INLET AND COASTAL REGION

1972 ◽  
Vol 1 (13) ◽  
pp. 44
Author(s):  
Pang-Mou Lin
Keyword(s):  
Sediment Transport ◽  
Coastal Region ◽  
Shear Stresses ◽  
Wave Steepness ◽  
Coastal Regions ◽  
Longshore Sediment Transport ◽  
Flume Tests ◽  
Bed Materials ◽  
The Relationship ◽  
Fluid Characteristic

Sediment transport In the vicinity of inlets and coastal regions depends on the combined bottom shear stresses due to both currents and waves. The modeling of the movement of bedload is controlled by the Proude law, bottom shear stress, wave steepness, and friction factor. Assuming Einstein's theory of bedload function can be applied to this study, an analysis was performed after conducting experiments in the flume and model basin. A series of results obtained from the flume tests is to Insure the relationship between the fluid characteristic and the movement of bedload. The final results concerning the longshore sediment transport appeared satisfactory with the estimated curves. The bottom configurations in the Inlet after each test were also shown satisfactorily similar. The sedimentologlcal time scale for the three bed materials were not In satisfactory agreement, however, more discussion of the results was presented in this paper.

scholarly journals Sediment Transport Beyond the Surf Zone Under Waves and Currents of the Non-Tidal Sea: Lubiatowo (Poland) Case Study

2016 ◽  
Vol 63 (1) ◽  
pp. 63-77 ◽  
Author(s):  
Rafał Ostrowski ◽  
Magdalena Stella
Keyword(s):  
Sediment Transport ◽  
Surf Zone ◽  
Coastal Region ◽  
Wave Climate ◽  
Soil Parameters ◽  
Shear Stresses ◽  
Research Station ◽  
Sea Bed ◽  
Waves And Currents ◽  
Bed Changes

Abstract The paper deals with the sandy coastal zone at Lubiatowo in Poland (the south Baltic Sea). The study comprises experimental and theoretical investigations of hydrodynamic and lithodynamic processes in the coastal region located close to the seaward boundary of the surf zone and beyond the surf zone. The analysis is based on field data collected at the IBW PAN Coastal Research Station in Lubiatowo. The data consist of wind velocity reconstructed from the long-term wave climate, deep-water wave buoy records and sea bottom soil parameters. Nearbed flow velocities induced by waves and currents, as well as bed shear stresses are theoretically modelled for various conditions to determine sediment motion regimes in the considered area. The paper discusses the possibility of occasional intensive sediment transport and the occurrence of distinct sea bed changes at bigger water depths.

scholarly journals LONGSHORE TRANSPORT EVALUATIONS AT A DETACHED BREAKWATER

1980 ◽  
Vol 1 (17) ◽  
pp. 86 ◽  
Author(s):  
R.O. Bruno ◽  
R.G. Dean ◽  
C.G. Gable
Keyword(s):  
Sediment Transport ◽  
Engineering Research ◽  
Pressure Transducers ◽  
Longshore Sediment Transport ◽  
Longshore Transport ◽  
Wave Energy Flux ◽  
Correlation Constant ◽  
Wave Induced ◽  
The Relationship ◽  
The Waves

A field experiment was conducted by the Coastal Engineering Research Center (CERC) to develop correlations between wave characteristics and longshore sediment transport. The waves were measured by two near-bottom mounted pressure transducers and the average longshore sediment transport rates were determined from sequential volumetric surveys behind an offshore breakwater which was regarded as a total trap. The data analyzed herein encompass a period of nine months during which a total accumulation of 675,000 m3 occurred as documented by eight surveys. Spectral analyses of the wave data were conducted and yielded one direction per frequency. The correlations include immersed weight sediment transport rate, I, versus (1) longshore component of wave energy flux at breaking, P&Sf and (2) the onshore flux of the longshore component of wave-induced momentum, S „. The most widely used correlation constant, K, in the relationship I = KPjig is 0,77. The best-fit values found from the data were K = 0.65 and 0.92 for linear and log best-fits, respectively, as based on the p£s values directed toward the trap. The corresponding values of KA (dimensional) relating I and Sxv are 4.98 m/s and 6.37 m/s, respectively. One feature of this type of trap is the potential for overtrapping if the waves are directed nearly normal to shore.

scholarly journals LONGSHORE TRANSPORT DETERMINED BY AN EFFICIENT TRAP

1982 ◽  
Vol 1 (18) ◽  
pp. 60 ◽  
Author(s):  
R.G. Dean ◽  
E.P. Berek ◽  
C.G. Gable ◽  
R.J. Seymour
Keyword(s):  
Sediment Transport ◽  
Field Component ◽  
Santa Barbara ◽  
Wave Characteristics ◽  
Nearshore Sediment Transport ◽  
Longshore Sediment Transport ◽  
Longshore Transport ◽  
Correlation Constant ◽  
The Relationship ◽  
Best Fit

The Nearshore Sediment Transport Study (NSTS), sponsored by the National Sea Grant Office included a field component to quantify the total longshore sediment transport relationship. This component was conducted at Santa Barbara, California and encompassed a period of eighteen months during which ten surveys were conducted. To date, eight of these surveys have been analyzed, yielding seven intersurvey periods. A total of 288,600 m3 of net sediment transport was documented by these eight surveys. The wave characteristics are based on one of two Sxy gages located in a water depth of 7 m. The most widely used correlation constant, K, in the relationship I = KP, is 0.77. The values found from the data were 0.93 and 1.23 for linear and log best-fit values, respectively. The corresponding values of K4 relating I and S are 2.60 and 2.63 m/s, respectively.

scholarly journals DISTRIBUTION OF SAND TRANSPORT RATE ACROSS A SURF ZONE

1978 ◽  
Vol 1 (16) ◽  
pp. 95 ◽  
Author(s):  
Toru Swaragi ◽  
Ichiro Deguchi
Keyword(s):  
Shear Stress ◽  
Sediment Transport ◽  
Surf Zone ◽  
Transport Rate ◽  
Sand Transport ◽  
Shear Stresses ◽  
Bottom Shear Stress ◽  
Longshore Current ◽  
Unidirectional Flow ◽  
Longshore Sediment Transport

The distributions of longshore and on-offshore sediment transport rates in a surf zone were measured by an apparatus which was able to separately record both components of the sediment transport rate,, The characteristics of their distributions were discussed from the bottom shear stresses which were measured by the shear meter under the same wave conditions as the laboratory experiment of the sediment transport. The maximum bottom shear stress took place at the depth between the breaking depth of waves and the depth where the velocity of the longshore current showed a maximum. On the other hand, the maximum on-offshore and longshore sediment transport rates occured at the depth slightly shallower than the depth where the maximum bottom shear stress took place. What's more, the longshore sediment transport rates were represented by the longshore current velocity and the bottom shear stress generated by waves and the longshore current. However, the distribution of the on-offshore sediment transport rates showed more complicated profile than that of the longshore sediment transport rates because there were no eminent unidirectional flow in the direction normal to the shore line. Therefore, the on-offshore sediment transport rates could not be formulated by the bottom shear stresses.

Sea wave propagation from offshore to Maputo's coast. Application to longshore sediment transport assessment

2014 ◽  
Vol 69 (12) ◽  
pp. 2438-2445
Author(s):  
Cristina N. A. Viola ◽  
Manel Grifoll ◽  
Jaime Palalane ◽  
Tiago C. A. Oliveira
Keyword(s):  
Wave Propagation ◽  
Sediment Transport ◽  
Coastal Region ◽  
Wave Theory ◽  
Wave Climate ◽  
Linear Wave ◽  
Engineering Research ◽  
Longshore Sediment Transport ◽  
Mesh Resolution ◽  
Offshore Wave

This study aims to characterize the wave climate near the coastal region of Maputo (Mozambique), and to provide a first assessment of the sediment transport load in this area. A time-series of 13 years' worth of offshore wave data, obtained from reanalysis products, was propagated to the coast. Wave propagation was performed using Linear Wave theory and the numerical model, Simulating WAves Nearshore (SWAN). Propagations with SWAN were carried out considering different scenarios in order to evaluate the influence of parameters such as wind, tidal level, frequency spectrum and numerical mesh resolution on wave characteristics along the coast. The prevalent waves propagated came from between east and southwest directions. Results from linear propagation were used to estimate the potential longshore sediment transport. The Coastal Engineering Research Center formula was applied for a stretch of beach in the Machangulo Peninsula. A net potential rate of longitudinal sediment transport (of the order of 105 m3/year, along an extension of the coast of 21 km) was directed northwards, and was consistent with the frequent wave directions.

scholarly journals On Uncertainties in Determination of Sediment Transport Rates in Coastal Regions

2016 ◽  
Vol 63 (4) ◽  
pp. 265-280
Author(s):  
Rafał Ostrowski
Keyword(s):  
Sediment Transport ◽  
Wave Transformation ◽  
Shear Stresses ◽  
Coastal Regions ◽  
Graded Properties ◽  
Physical Phenomena ◽  
Bed Shear Stresses ◽  
Coastal Hydrodynamics ◽  
Sediment Resources

Abstract The paper deals with research uncertainties, difficulties, inaccuracies and unreliabilities related to the modelling of physical phenomena involving coastal lithodynamics. The considerations are focused on processes of wave transformation, wave-driven currents and sediment transport itself. It is shown that possible inaccuracies at individual stages of the modelling of coastal hydrodynamics can lead to serious uncertainties with respect to the ultimate modelling output, namely bed shear stresses and sediment transport rates. These inaccuracies result mostly from arbitrarily assumed parameters and constants. Other modelling biases discussed in the paper comprise simplifications and approximations with respect to sediment resources and size-graded properties, randomness of hydrodynamic impacts, bottom roughness and land-borne factors involved in coastal lithodynamics.

STUDY ON LONGSHORE SEDIMENT TRANSPORT USING CIRCULAR WAVE BASIN

2019 ◽  
Vol 75 (2) ◽  
pp. I_625-I_630
Author(s):  
Naoki AKITA ◽  
Risa KATO ◽  
Hoang Hai DONG ◽  
Tomoaki NAKUMURA ◽  
Norimi MIZUTANI
Keyword(s):  
Sediment Transport ◽  
Longshore Sediment Transport ◽  
Wave Basin

2D and 3D CFD Investigations of Seabed Shear Stresses Around Subsea Pipelines

2013 ◽  
Author(s):  
Wenwen Shen ◽  
Terry Griffiths ◽  
Mengmeng Xu ◽  
Jeremy Leggoe
Keyword(s):  
Sediment Transport ◽  
Suspended Sediment ◽  
Interaction Model ◽  
Suspended Sediment Transport ◽  
Shear Stresses ◽  
Parametric Function ◽  
Ample Evidence ◽  
North West ◽  
Wide Range ◽  
Subsea Pipelines

For well over a decade it has been widely recognised that existing models and tools for subsea pipeline stability design fail to account for the fact that seabed soils tend to become mobile well before the onset of pipeline instability. Despite ample evidence obtained from both laboratory and field observations that sediment mobility has a key role to play in understanding pipeline/soil interaction, no models have been presented previously which account for the tripartite interaction between the fluid and the pipe, the fluid and the soil, and the pipe and the soil. There are numerous well developed and widely used theories available to model pipe-fluid and pipe-soil interactions. A challenge lies in the way to develop a satisfactory fluid-soil interaction algorithm that has the potential for broad implementation under both ambient and extreme sea conditions due to the complexity of flow in the vicinity of a seabed pipeline or cable. A widely used relationship by Shields [1] links the bedload and suspended sediment transport to the seabed shear stresses. This paper presents details of computational fluid dynamics (CFD) research which has been undertaken to investigate the variation of seabed shear stresses around subsea pipelines as a parametric function of pipeline spanning/embedment, trench configuration and wave/current properties using the commercial RANS-based software ANSYS Fluent. The modelling work has been undertaken for a wide range of seabed geometries, including cases in 3D to evaluate the effects of finite span length, span depth and flow attack angle on shear stresses. These seabed shear stresses have been analysed and used as the basis for predicting sediment transport within the Pipe-Soil-Fluid (PSF) Interaction Model [2] in determining the suspended sediment concentration and the advection velocity in the vicinity of pipelines. The model has significant potential to be of use to operators who struggle with conventional stabilisation techniques for the pipelines, such as those which cross Australia’s North West Shelf, where shallow water depths, highly variable calcareous soils and extreme metocean conditions driven by frequent tropical cyclones result in the requirement for expensive and logistically challenging secondary stabilisation measures.

Revisiting the derivation of bulk longshore sediment transport rates using meta-heuristic algorithms

2021 ◽  
Vol 69 ◽  
Author(s):  
Zahra Gholami ◽  
Kamran Lari ◽  
Abbasali Aliakbari Bidokhti ◽  
AmirHosein Javid
Keyword(s):  
Sediment Transport ◽  
Heuristic Algorithms ◽  
Longshore Sediment Transport
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