Numerical modelling of flow around coastal structures and scour prediction
TL;DR: In this article, the numerical prediction of nearshore circulation induced due to wave setup in the nearshore region with and without the structure (i) structure resting on seabed (ii) structure raised above the seafloor).
About: This article is published in Ocean Engineering.The article was published on 2002-04-01. It has received 7 citations till now. The article focuses on the topics: Wave setup & Seabed.
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TL;DR: A review of the recent development of numerical modelling of local scour around hydraulic and marine structures is presented in this article , where the authors classify numerical models for simulating local sediment scour into five categories: sediment transport rate models, two-phase models, CFD-DEM models, equilibrium scour models, and depth-averaged models.
Abstract: This paper reviews the recent development of numerical modelling of local scour around hydraulic and marine structures. The numerical models for simulating local scour are classified into five categories: sediment transport rate models, two-phase models, CFD-DEM models, equilibrium scour models and depth-averaged models. The sediment transport rate models are the most popularly used models because of their high calculation speed and availability of empirical formulae for predicting sediment transport rates. Two-phase models were developed to simulate sediment transport in the format of sheet flow under strong current velocity or strong turbulence. The CFD-DEM model simulates the motion of every individual sediment particle. Its speed is the slowest, but it provides the opportunity to understand fundamental mechanisms of flow–particle interaction and particle–particle interaction using small-scale simulations. Equilibrium scour models predict the final scour profile at the equilibrium stage but cannot predict scour history. The depth-averaged models that were developed early are not recommended for local scour problems because they are not able to predict three-dimensional features around structures. Although many numerical models have been developed and many studies have been conducted to investigate local scour, some challenging problems remain to be solved, for example, the effects from scaling and sediment gradation. In addition, people’s understanding of local scour of cohesive sand is still very shallow, and more experimental and numerical research in this area is needed.
6 citations
TL;DR: The authors examines some of the key sources of error when working with historical tide gauge records in local geographic areas and aims to identify the limitations of locally derived data thereby assisting in the determination of relative sea level trends that are of widespread value to infrastructure and policy makers.
Abstract: The Intergovernmental Panel on Climate Change (IPCC) considers eustatic sea level rise to be a major impact driven by climate change. Relative sea level change, whether positive or negative, will affect industries, communities and ecology along the world’s coastlines and estuaries. Estimates of global eustatic sea level rise between 1961 and 2003 are 1.8 ± 0.5 mm a−1, reflecting results from validated global tide gauge records. Over the last two decades, several studies have used automatic tide gauge records with at least 80 years of data to generate global prediction models. The IPCC recognises that global change is not uniform, therefore local policy for flood management and coastal protection should rely on local change models that incorporate glacio-isostatic adjustment (GIA) and apply accurate data correction techniques. Some of the longest tidal records are held within the Northern Hemisphere, e.g. Cascais, Amsterdam, Aberdeen, Sheerness and Newlyn. The UK provides several important case studies highlighting changes in relative sea level between the north and the south, primarily due to variations in GIA rates of land uplift and subsidence. Tide gauge records are held by a variety of governmental, non-governmental and private organisations. However, each source may typically compile data in different ways, relying on diverse equipment and recording techniques, often with variations in frequency, length, quality and corrections applied. Even within a single organisation there may be differences in dataset quality. This paper examines some of the key sources of error when working with historical tidal datasets in local geographic areas and aims to identify the limitations of locally derived data thereby assisting in the determination of relative sea level trends that are of widespread value to infrastructure and policy makers.
4 citations
Cites background from "Numerical modelling of flow around ..."
...Aggressive storm surges and wave interaction can remove sand from beaches and damage defence structures threatening tourism (Jyothi et al. 2002) and other infrastructure....
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...Changes to relative sea level will influence coastal geomorphology, nearshore circulation and erosion patterns, thereby adding more potential damage to the shoreline (Jyothi et al. 2002) in a rising scenario....
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19 Nov 2019
TL;DR: In this paper, a simulation of sand sediment of 1 mm sand particles in the fluid flow of water using Discrete Particle Method-Discrete Element Method (DPM-DEM) to understand the behavior of sand particle in fluid flow.
Abstract: The changes of shoreline profile are a natural phenomenon that occur on worldwide site and became concern of many researchers. Due to natural forces such as wind and wave of the seawater, the formation of shoreline can be changes and leads to erosion. Eventually, this work is aimed to conduct a simulation of sand sediment of 1 mm sand particles in the fluid flow of water using Discrete Particle Method-Discrete Element Method (DPM-DEM) to understanding the behavior of sand particle in the fluid flow. The simulation works reported that, the maximum velocity of 1 mm sand particle is 0.582127 m/s for every time step while the minimum velocity is varying for each time step. It is also found that, the lengthen of time will increase the possibility for the erosion to occur. The most critical area was determined through this simulation and it shows that the upper part of the sand sediment has the high risk that can leads to erosion.
2 citations
06 Dec 2017
TL;DR: In this article, a coupled model of hydrodynamic model, spectral wave and sediment transport were conducted to study the pattern of sediment movement in order to understand the process of sediment transport caused by the dynamics of currents and waves on the basis of morphological changes.
Abstract: Interactions between sediments in the marine environment with the dynamics of the ocean can generate sediment movement. Sedimentation and erosion is the result of these interactions, which often have a negative impact on the harbor waters or coastal environment. The purpose of this research is to understand the process of sediment transport caused by the dynamics of currents and waves on the basis of morphological changes and the potential that can lead to scour for coastal protection structures (groin).Coupled model of hydrodynamic model, spectral wave and sediment transport were conducted to study the pattern of sediment movement. Simulations carried out by varying the waveform specification that propagates to the domain model. Verification of maximum velocity magnitude due to Van Rijn (1987), Nurdjaman and Ningsih (2003), and Adilantip (2012) shows good agreement with the differences value below 5%. While verification of wave height and wave stress radiation with analytical calculation shows good comparison with the mean of differences value 15%. The results of the study indicate that scour depth of 0,955 m was formed at the end of the simulation by the discharge input only. When the discharge combined with the various wave height and periods, scour depth increases by about 3 - 14%. Location of the scour depth coincides with the location of the maximum velocity at the tip of the groin structures to the left side. Abstrak Interaksi antara sedimen di lingkungan laut dengan dinamika laut dapat menghasilkan pergerakan sedimen. Proses sedimentasi dan erosi merupakan hasil dari interaksi tersebut yang tak jarang berdampak negatif terhadap perairan pelabuhan ataupun lingkungan pesisir. Tujuan dari penelitian ini yaitu untuk memahami proses transpor sedimen yang diakibatkan oleh dinamika arus dan gelombang terhadap perubahan morfologi dasar dan potensinya yang dapat mengakibatkan gerusan terhadap struktur pelindung pantai (groin). Dilakukan model kopel hidrodinamika, gelombang spektral, dan transpor sedimen untuk mempelajari pola pergerakan sedimen. Simulasi dilakukan dengan memvariasikan perbedaan spesifikasi gelombang yang menjalar terhadap domain model. Simulasi dilakukan dengan memvariasikan spesifikasi waveform yang merambat ke model domain. Verifikasi besarnya kecepatan aliran maksimum dari hasil model oleh Van Rijn (1987), Nurdjaman dan Ningsih (2003), dan Adilantip (2012) menunjukkan kesesuaian yang baik dengan perbedaan nilai di bawah 5%. Sedangkan verifikasi tinggi gelombang dan radiasi tegangan gelombang dengan perhitungan analitik menunjukkan perbandingan yang baik dengan rata-rata perbedaan nilai 15%. Hasil penelitian menunjukkan bahwa kedalaman gerusan 0,955 m terbentuk pada akhir simulasi dengan input debit sungai saja. Bila ddebit sungai dikombinasikan dengan berbagai tinggi dan perioda gelombang, kedalaman gerusan meningkat sekitar 3 - 14%. Lokasi kedalaman gerusan bertepatan dengan lokasi kecepatan aliran maksimum pada ujung struktur groin sisi kiri.
1 citations
14 Feb 2012
TL;DR: In this paper, wave-induced circulation in general coastal environments is simulated by coupling two widely-used finite-element models, namely, a refraction-diffraction-reflection model based on the elliptic mild-slope equation, and a two-dimensional (depth-averaged) shelf-scale circulation model.
Abstract: Integration of Different Wave Forcing Formulations with Nearshore Circulation Models. (December 2010) Abhishek Sharma, B.S., Institute of Technology, Banaras Hindu University (BHU) Co-Chairs of Advisory Committee: Dr. Vijay Panchang, Dr. Jennifer Irish Wave-induced circulation in general coastal environments is simulated by coupling two widely-used finite-element models, namely, a refraction-diffractionreflection model based on the elliptic mild-slope equation, and a two-dimensional (depth-averaged) shelf-scale circulation model. Such models yield wave-induced current-fields and set-up/down. This involves exploration of some numerical and practical issues, for example, the selection of appropriate boundary condition and grid resolution, numerical errors owing to higher-order derivatives, etc. Computations of the wave forcing from the elliptic wave model, and the wave-induced quantities from the circulation model, are validated with theoretical and published results. The coupled system is then used to simulate the wave-induced circulation in the domains where structures (e.g. breakwater, jetty, etc.) and bathymetric features (e.g. shoal, etc.) are present. In practice, usually an approximate form of the wave-induced forcing is used. This has certain limitations in some application, which have been poorly studied so far. Therefore, here we consider two alternative approaches. The performance of these wave
1 citations
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74 citations
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01 Jan 1988
73 citations
TL;DR: In this paper, a numerical model for nearshore current analyses is presented and comparative studies of various methods of unsteady and steady flow analyses including both explicit and implicit schemes are made.
Abstract: This paper deals with a numerical model for nearshore current analyses. Various methods of unsteady and steady flow analyses including both explicit and implicit schemes are introduced and comparative studies are made on them. Discussions are extended to the techniques to maintain the stability and to prompt the convergence of computations. Results of trial analyses are shown and compared with those of physical experiments on currents around a breakwater and a jetty.
8 citations