scholarly journals Controls on submarine canyon connection to the shoreline: a numerical modelling approach

2021 ◽  
Author(s):  
Euan Soutter ◽  
Ian Kane ◽  
David Hodgson ◽  
Stephen Flint
Keyword(s):  
Numerical Model ◽  
Numerical Models ◽  
Submarine Canyon ◽  
Sediment Supply ◽  
Exact Nature ◽  
Submarine Canyons ◽  
Empirical Relationships ◽  
Sediment Transfer ◽  
Sediment Export ◽  
Modelling Approach

Submarine canyons with heads located close to shorelines, known as shore-connected canyons, provide a focussed pathway for basinward sediment transport. Placing greater constraints on the key parameters that control the formation of shore-connected canyons can help us predict the efficiency of sediment export to deep-water under different environmental conditions and through time. Using a numerical model incorporating geomorphic principles, we show that shore-connected canyons are most active when fluvial discharge is high, the continental shelf is steep and narrow, and the magnitude of relative sea-level change is high. The numerical model reproduces observed bathymetric distributions of shore-connected submarine canyons, indicating that the empirical relationships underlying these numerical models are accurate descriptions of shore-connected canyon formation in nature. Our study provides constraints on the key quantifiable parameters controlling shore-connected submarine canyon formation and maintenance, such as fluvial discharge and basin physiography, allowing for more accurate predictions of the efficiency and timing of sediment transfer to the deep sea under different conditions. The model results suggest that; 1) submarine canyons may form frequently on the slope due to submarine processes, but subaerial processes control which submarine canyons are most likely to connect to the shoreline, 2) margin physiography and sediment supply are more influential in driving submarine canyon incision across the shelf and sediment transfer than the exact nature of the gravity flow triggering mechanism, and 3) the stratigraphic records of shore-connected submarine canyons and fans are more influenced by onshore climate and tectonics than eustasy.

scholarly journals Storm-induced sediment supply to coastal dunes on sand flats

2020 ◽  
Vol 8 (2) ◽  
pp. 335-350 ◽  
Author(s):  
Filipe Galiforni-Silva ◽  
Kathelijne M. Wijnberg ◽  
Suzanne J. M. H. Hulscher
Keyword(s):  
Numerical Model ◽  
Storm Surge ◽  
Storm Surges ◽  
Coastal Dunes ◽  
Sediment Supply ◽  
Aeolian Transport ◽  
Sand Flat ◽  
Sediment Transfer ◽  
Sand Flats

Abstract. Growth of coastal dunes requires a marine supply of sediment. Processes that control the sediment transfer between the subtidal and the supratidal zone are not fully understood, especially in sand flats close to inlets. It is hypothesised that storm surge events induce sediment deposition on sand flats, providing fresh material for aeolian transport and dune growth. The objective of this study is to identify which processes cause deposition on the sand flat during storm surge conditions and discuss the relationship between the supratidal deposition and sediment supply to the dunes. We use the island of Texel (NL) as a case study, of which multiannual topographic and hydrographic datasets are available. Additionally, we use the numerical model XBeach to simulate the most frequent storm surge events for the area. Results show that supratidal shore-parallel deposition of sand occurs in both the numerical model and the topographic data. The amount of sand deposited is directly proportional to surge level and can account for more than a quarter of the volume deposited at the dunes yearly. Furthermore, storm surges are also capable of remobilising the top layer of sediment of the sand flat, making fresh sediment available for aeolian transport. Therefore, in a sand flat setting, storm surges have the potential of reworking significant amounts of sand for aeolian transport in periods after the storm and as such can also play a constructive role in coastal dune development.

scholarly journals MECHANISM OF OFFSHORE SAND DISCHARGE INTO SUBMARINE CANYON TRIGGERED BY CONSTRUCTING DETACHED BREAKWATER CLOSE TO SHORELINE

2011 ◽  
Vol 1 (32) ◽  
pp. 18
Author(s):  
Koji Yamada ◽  
Takaaki Uda ◽  
Yoshio Suwa ◽  
Toshiro San-nami ◽  
Kou Furuike ◽  
...  
Keyword(s):  
Survey Data ◽  
Submarine Canyon ◽  
Sediment Supply ◽  
Beach Erosion ◽  
Aerial Photographs ◽  
Sand Transport ◽  
Submarine Canyons ◽  
Bathymetric Survey ◽  
Bed Slope

Several submarine canyons have developed offshore of the Aramata region of the Shimoni-ikawa coast in Toyama Bay, which is one of the three deep bays in Japan. The Kurobe River with a steep bed slope flows into the sea immediately north of this region, and a large amount of sediment has been supplied to this area, which has been transported by southward longshore sand transport. However, beach erosion has occurred owing to the decrease in sediment supply from the Kurobe River. Furthermore, since the construction of detached breakwaters as a measure against beach erosion, offshore sand transport has accelerated and beach erosion has become more severe. In this study, aerial photographs and bathymetric survey data were analyzed, then the mechanism of offshore sand transport was investigated using the BG model proposed by Serizawa et al. (2007).

scholarly journals Validation of Fiber-Based Distributed Plasticity Approach for Steel Bracing Models

2015 ◽  
Vol 1 (2) ◽  
pp. 1-13 ◽  
Author(s):  
Alper Kanyilmaz
Keyword(s):  
Numerical Model ◽  
Nonlinear Analysis ◽  
Numerical Models ◽  
Hysteresis Loops ◽  
Computation Time ◽  
Experimental Result ◽  
Analysis Approach ◽  
Element Formulation ◽  
Nonlinear Behaviour ◽  
Modelling Approach

Nonlinear analysis approach is not anymore limited only to research purposes, but becoming more popular as a tool that can be used during design, thanks to the increased efficiency of computer software and hardware. An accurately calibrated numerical model may simulate the behaviour of buildings in a quite realistic way, which helps designers understand better the performance of their structures. However, the feasibility of the nonlinear analysis approach is limited by the complexity of the numerical model, and the aim of any researcher or engineer is to obtain the most useful information in a reasonable amount of time. This study focuses on the validation of a simplified numerical modelling approach to simulate the nonlinear behaviour of steel bracings. The paper presents a comparison between two different modelling approaches; a refined finite element model using volumetric elements, and fiber-based model using beam elements with distributed plasticity. The numerical models calibrated with the experimental result from existing literature, reproduce the behaviour of cold formed square, and hot rolled open section steel elements under inelastic cyclic loading. The hysteresis loops obtained from two models show that the accuracy obtained by simpler fiber-element formulation is quite close to the more refined volumetric model. Finally, in order to assess the accuracy of the fiber-based modelling approach to estimate the nonlinear cyclic response of full-scale braced frame configurations, two real scale frames are analysed, and the results are compared with the results of the experiments performed on the test frames. In terms of computation time and accuracy, distributed plasticity model is much more efficient, and can be a good option to perform nonlinear analysis of multi-level buildings, which would be quite cumbersome with volumetric modelling approach. This study has been realized thanks to the research fund received from European commission with the contract MEAKADO RFSR-CT-2013-00022.

scholarly journals QUANTITATIVE PREDICTION OF SAND DISCHARGE INTO SUBMARINE CANYON OFF MORITO RIVER ON SEISHO COAST, JAPAN

2011 ◽  
Vol 1 (32) ◽  
pp. 107 ◽  
Author(s):  
Kou Furuike ◽  
Takaaki Uda ◽  
Masumi Serizawa ◽  
Toshiro San-nami ◽  
Toshinori Ishikawa
Keyword(s):  
Grain Size ◽  
Size Composition ◽  
Submarine Canyon ◽  
Sediment Supply ◽  
Quantitative Prediction ◽  
Change Model ◽  
Submarine Canyons ◽  
Equilibrium Conditions ◽  
Grain Size Composition

On the Seisho coast, submarine canyons have developed very close to the shoreline and the discharge of fluvial sediment of the Sakawa River into the submarine canyons has been reported, resulting in the net loss of sand into the offshore zone. The beach topography under dynamically equilibrium conditions owing to the sediment supply from the river and the sand loss into the submarine canyons during several thousand years was reproduced using the contour-line-change model considering the grain size composition. Long-term beach changes around the submarine canyons were accurately predicted and the effect of beach nourishment using a mixture of fine and coarse materials was investigated.

scholarly journals A Computational Approach to Solve a System of Transcendental Equations with Multi-Functions and Multi-Variables

Mathematics ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 920
Author(s):  
Chukwuma Ogbonnaya ◽  
Chamil Abeykoon ◽  
Adel Nasser ◽  
Ali Turan
Keyword(s):  
Numerical Models ◽  
Problem Formulation ◽  
Science And Engineering ◽  
Physical Systems ◽  
Engineering Problems ◽  
Parametric Studies ◽  
Independent Variable ◽  
Transcendental Equations ◽  
The Waves ◽  
Modelling Approach

A system of transcendental equations (SoTE) is a set of simultaneous equations containing at least a transcendental function. Solutions involving transcendental equations are often problematic, particularly in the form of a system of equations. This challenge has limited the number of equations, with inter-related multi-functions and multi-variables, often included in the mathematical modelling of physical systems during problem formulation. Here, we presented detailed steps for using a code-based modelling approach for solving SoTEs that may be encountered in science and engineering problems. A SoTE comprising six functions, including Sine-Gordon wave functions, was used to illustrate the steps. Parametric studies were performed to visualize how a change in the variables affected the superposition of the waves as the independent variable varies from x1 = 1:0.0005:100 to x1 = 1:5:100. The application of the proposed approach in modelling and simulation of photovoltaic and thermophotovoltaic systems were also highlighted. Overall, solutions to SoTEs present new opportunities for including more functions and variables in numerical models of systems, which will ultimately lead to a more robust representation of physical systems.

scholarly journals Preliminary Results on the Dynamics of a Pile-Moored Fish Cage with Elastic Net in Currents and Waves

2020 ◽  
Vol 9 (1) ◽  
pp. 14
Author(s):  
Gianluca Zitti ◽  
Nico Novelli ◽  
Maurizio Brocchini
Keyword(s):  
Numerical Model ◽  
Laboratory Experiments ◽  
Numerical Models ◽  
Offshore Structures ◽  
Fish Farm ◽  
Maximum Displacement ◽  
Drag Forces ◽  
Real Size ◽  
Lift And Drag ◽  
Mesh Grid

Over the last decades, the aquaculture sector increased significantly and constantly, moving fish-farm plants further from the coast, and exposing them to increasingly high forces due to currents and waves. The performances of cages in currents and waves have been widely studied in literature, by means of laboratory experiments and numerical models, but virtually all the research is focused on the global performances of the system, i.e., on the maximum displacement, the volume reduction or the mooring tension. In this work we propose a numerical model, derived from the net-truss model of Kristiansen and Faltinsen (2012), to study the dynamics of fish farm cages in current and waves. In this model the net is modeled with straight trusses connecting nodes, where the mass of the net is concentrated at the nodes. The deformation of the net is evaluated solving the equation of motion of the nodes, subjected to gravity, buoyancy, lift, and drag forces. With respect to the original model, the elasticity of the net is included. In this work the real size of the net is used for the computation mesh grid, this allowing the numerical model to reproduce the exact dynamics of the cage. The numerical model is used to simulate a cage with fixed rings, based on the concept of mooring the cage to the foundation of no longer functioning offshore structures. The deformations of the system subjected to currents and waves are studied.

scholarly journals Development of Detailed FE Numerical Models for Assessing the Replacement of Metal with Composite Materials Applied to an Executive Aircraft Wing

Aerospace ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 178
Author(s):  
Valerio Acanfora ◽  
Roberto Petillo ◽  
Salvatore Incognito ◽  
Gerardo Mario Mirra ◽  
Aniello Riccio
Keyword(s):  
Composite Material ◽  
Composite Materials ◽  
Numerical Model ◽  
Numerical Models ◽  
Structural Performance ◽  
Aircraft Wing ◽  
Resin Infusion ◽  
Effectiveness Analysis ◽  
Liquid Resin Infusion ◽  
Process Constraints

This work provides a feasibility and effectiveness analysis, through numerical investigation, of metal replacement of primary components with composite material for an executive aircraft wing. In particular, benefits and disadvantages of replacing metal, usually adopted to manufacture this structural component, with composite material are explored. To accomplish this task, a detailed FEM numerical model of the composite aircraft wing was deployed by taking into account process constraints related to Liquid Resin Infusion, which was selected as the preferred manufacturing technique to fabricate the wing. We obtained a geometric and material layup definition for the CFRP components of the wing, which demonstrated that the replacement of the metal elements with composite materials did not affect the structural performance and can guarantee a substantial advantage for the structure in terms of weight reduction when compared to the equivalent metallic configuration, even for existing executive wing configurations.

A physically-based soil surface model and its combination with numerical models for predicting bare-soil evaporation rates

2021 ◽  
Author(s):  
Xiaocheng Liu ◽  
Chenming Zhang ◽  
Yue Liu ◽  
David Lockington ◽  
Ling Li
Keyword(s):  
Numerical Model ◽  
Surface Resistance ◽  
Numerical Models ◽  
Soil Column ◽  
Soil Surface ◽  
Bare Soil ◽  
Water Vapor Transport ◽  
Surface Model ◽  
Vapor Flow ◽  
Physically Based

<p>Estimation of evaporation rates from soils is significant for environmental, hydrological, and agricultural purposes. Modeling of the soil surface resistance is essential to estimate the evaporation rates from bare soil. Empirical surface resistance models may cause large deviations when applied to different soils. A physically-based soil surface model is developed to calculate the surface resistance, which can consider evaporation on the soil surface when soil is fully saturated and the vapor flow below the soil surface after dry layer forming on the top. Furthermore, this physically-based expression of the surface resistance is added into a numerical model that considers the liquid water transport, water vapor transport, and heat transport during evaporation. The simulation results are in good agreement with the results from six soil column drying experiments.  This numerical model can be applied to predict or estimate the evaporation rate of different soil and saturation at different depths during evaporation.</p>

Embedding compaction processes in long-term evolution modeling of tidal marshes

2021 ◽  
Author(s):  
Riccardo Xotta ◽  
Claudia Zoccarato ◽  
Philip S. J. Minderhoud ◽  
Pietro Teatini
Keyword(s):  
Numerical Model ◽  
Marsh Surface ◽  
Long Term Evolution ◽  
Sediment Supply ◽  
Tidal Marshes ◽  
High Porosity ◽  
Fe Method ◽  
Geomechanical Properties ◽  
Term Evolution

<p>Tidal marshes are vulnerable and dynamic ecosystems with essential roles from protection against marine storms to biodiversity preservation. However, the survival of these environments is threatened by external stressors such as increasing mean sea level, reduction in sediment supply, and erosion. Tidal marshes are formed by deposition over the last centuries to millennia of sediments transported by surface water and biodegradation of organic matter derived from halophytic vegetation. Therefore, the sediment at the surface is characterized by high porosity and their large consolidation potential plays an important role in the future elevation dynamics, which is often not fully recognized.</p><p>Here we propose a novel three-dimensional numerical model to simulate the long-term dynamics of tidal marshes. A 3D groundwater flow equation in saturated conditions is implemented to compute the over-pressure dissipation with the aid of the finite element (FE) method, whereas the sediment consolidation is computed according to Terzaghi's theory.</p><p>A Lagrangian approach is implemented in the FE numerical model to properly consider the large soil deformation arising from the deposition of highly compressible material. The hydro-geomechanical properties, that depend on the intergranular effective stress, are highly non-linear.</p><p>The model takes advantage of a dynamic mesh that simulates the evolution of the landform elevation by means of an accretion/compaction mechanism: the elements deform in time as the soil consolidates and increase in number as the new sediments deposit over the marsh surface. The deposition is treated as input to the consolidation model and can vary in space and time.</p><p>The model is applied to simulate the long-term evolution of realistic tidal marshes in terms of accretion and consolidation due to the coupled dynamics of surficial and subsurface processes.</p>

The Research of Energy Conversion and Heat Transfer in the Ceramic Foams of Solar Energy Converter

2011 ◽  
Author(s):  
Yangbo Deng ◽  
Fengmin Su ◽  
Chunji Yan
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Solar Radiation ◽  
Solar Energy ◽  
Numerical Models ◽  
Air Flow ◽  
Energy Converter ◽  
Ceramic Foams ◽  
Numerical Studies ◽  
Flow Through

The solar energy converter in Concentrated Solar Power (CSP) system, applies the solid frame structure of the ceramic foams to receive the concentrated solar radiation, convert it into thermal energy, and heat the air flow through the ceramic foams by convection heat transfer. In this paper, first, the pressure drops in the studied ceramic foams were measured under all kinds of flow condition. Based on the experimental results, an empirical numerical model was built for the air flow through ceramic foams. Second, a 3-D numerical model was built, for the receiving and conversion of the solar energy in the ceramic foams of the solar energy converter. Third, applying two aforementioned numerical models, the numerical studies of the thermal performance were carried out, for the solar energy converter filled with the ceramic foams, and results show that the structure parameters of the ceramic foams, the effective reflective area and the solar radiation intensity of the solar concentrator, have direct impacts on the absorptivity and conversion efficiency of the solar energy in the solar energy converter. And the results of the numerical studies are found to be in reasonable agreement with the experimental measurements. This paper will provide a reference for the design and manufacture of the solar energy converter with the ceramic foams.

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