scholarly journals RANS SIMULATION OF BREAKER BAR DEVELOPMENT USING A STABILIZED TURBULENCE MODEL

2020 ◽  
pp. 15
Author(s):  
Bjarke Eltard Larsen ◽  
David R. Fuhrman
Keyword(s):  
Sediment Transport ◽  
Turbulence Model ◽  
Surf Zone ◽  
Morphological Evolution ◽  
Turbulence Closure ◽  
Simulated Evolution ◽  
Rans Simulation ◽  
Closure Models ◽  
Rans Models

The results demonstrate the significant advantages of utilizing formally stabilized turbulence closure models in accurately predicting the surf zone dynamics, sediment transport, and breaker bar morphology in the shoaling region and in the outer surf zone using RANS models. Simulated evolution using a stabilized turbulence model is demonstrated to predict cross-shore breaker bar position, growth and evolution. This is in contrast to results using (otherwise identical) standard turbulence closure, which tend to flush the bar further offshore. Further improvements are still needed to increase hydrodynamic accuracy, hence sediment transport and morphological evolution, in the inner surf zone.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/R_sm_06qQGM

scholarly journals ENVIRONMENTAL FLOW AND CONTAMINANT TRANSPORT MODELING IN THE AMAZONIAN WATER SYSTEM BY USING Q3DRM1.0 SOFTWARE

2020 ◽  
Vol 5 (12) ◽  
pp. 377-391
Author(s):  
Li-ren Yu ◽  
Jun Yu
Keyword(s):  
Numerical Simulation ◽  
Contaminant Transport ◽  
Turbulence Model ◽  
Environmental Flows ◽  
Water System ◽  
Turbulence Models ◽  
Environmental Flow ◽  
Turbulence Closure ◽  
Strong Mixing ◽  
Closure Models

This paper reports a fine numerical simulation of environmental flow and contaminant transport in the Amazonian water system near the Anamã City, Brazil, solved by the Q3drm1.0 software, developed by the Authors, which can provide the different closures of three depth-integrated two-equation turbulence models. The purpose of this simulation is to refinedly debug and test the developed software, including the mathematical model, turbulence closure models, adopted algorithms, and the developed general-purpose computational codes as well as graphical user interfaces (GUI). The three turbulence models, provided by the developed software to close non-simplified quasi three-dimensional hydrodynamic fundamental governing equations, include the traditional depth-integrated two-equation turbulence   model, the depth-integrated two-equation turbulence model, developed previously by the first Author of the paper, and the depth-integrated two-equation turbulence   model, developed recently by the Authors of this paper. The numerical simulation of this paper is to solve the corresponding discretized equations with collocated variable arrangement on the non-orthogonal body-fitted coarse and fine two-levels’ grids. With the help of Q3drm1.0 software, the steady environmental flows and transport behaviours have been numerically investigated carefully; and the processes of contaminant inpouring as well as plume development, caused by the side-discharge from a tributary of the south bank (the right bank of the river), were also simulated and discussed in detail. Although the three turbulent closure models, used in this calculation, are all applicable to the natural rivers with strong mixing, the comparison of the computational results by using the different turbulence closure models shows that the turbulence   model with larger turbulence parameter provides the possibility for improving the accuracy of the numerical computations of practical problems.

scholarly journals Evaluation of turbulence closure models under spilling and plunging breakers in the surf zone

2016 ◽  
Vol 114 ◽  
pp. 177-193 ◽  
Author(s):  
S.A. Brown ◽  
D.M. Greaves ◽  
V. Magar ◽  
D.C. Conley
Keyword(s):  
Surf Zone ◽  
Turbulence Closure ◽  
Closure Models

Application of remote sensing technology to the relation of submarine pipelines and coastal morphology

1995 ◽  
Vol 32 (2) ◽  
pp. 77-83
Author(s):  
Y. Yüksel ◽  
D. Maktav ◽  
S. Kapdasli
Keyword(s):  
Remote Sensing ◽  
Sediment Transport ◽  
Surf Zone ◽  
Hydrodynamic Forces ◽  
Construction Site ◽  
Coastal Morphology ◽  
Remote Sensing Technology ◽  
Sensing Technology ◽  
Sea Bed

Submarine pipelines must be designed to resist wave and current induced hydrodynamic forces especially in and near the surf zone. They are buried as protection against forces in the surf zone, however this procedure is not always feasible particularly on a movable sea bed. For this reason the characteristics of the sediment transport on the construction site of beaches should be investigated. In this investigation, the application of the remote sensing method is introduced in order to determine and observe the coastal morphology, so that submarine pipelines may be protected against undesirable seabed movement.

scholarly journals Modelling of sediment transport and morphological evolution under the combined action of waves and currents

Ocean Science ◽  
2017 ◽  
Vol 13 (5) ◽  
pp. 673-690 ◽  
Author(s):  
Guilherme Franz ◽  
Matthias T. Delpey ◽  
David Brito ◽  
Lígia Pinto ◽  
Paulo Leitão ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Morphological Changes ◽  
Morphological Evolution ◽  
Research Effort ◽  
Beach Erosion ◽  
Model Complexity ◽  
Invariant Equilibrium ◽  
Waves And Currents ◽  
Combined Action ◽  
Modelling System

Abstract. Coastal defence structures are often constructed to prevent beach erosion. However, poorly designed structures may cause serious erosion problems in the downdrift direction. Morphological models are useful tools to predict such impacts and assess the efficiency of defence structures for different scenarios. Nevertheless, morphological modelling is still a topic under intense research effort. The processes simulated by a morphological model depend on model complexity. For instance, undertow currents are neglected in coastal area models (2DH), which is a limitation for simulating the evolution of beach profiles for long periods. Model limitations are generally overcome by predefining invariant equilibrium profiles that are allowed to shift offshore or onshore. A more flexible approach is described in this paper, which can be generalised to 3-D models. The present work is based on the coupling of the MOHID modelling system and the SWAN wave model. The impacts of different designs of detached breakwaters and groynes were simulated in a schematic beach configuration following a 2DH approach. The results of bathymetry evolution are in agreement with the patterns found in the literature for several existing structures. The model was also tested in a 3-D test case to simulate the formation of sandbars by undertow currents. The findings of this work confirmed the applicability of the MOHID modelling system to study sediment transport and morphological changes in coastal zones under the combined action of waves and currents. The same modelling methodology was applied to a coastal zone (Costa da Caparica) located at the mouth of a mesotidal estuary (Tagus Estuary, Portugal) to evaluate the hydrodynamics and sediment transport both in calm water conditions and during events of highly energetic waves. The MOHID code is available in the GitHub repository.

scholarly journals SURVEY TECHNIQUES/PROCEDURES AND DATA PROCESSING FOR MONITORING NEARSHORE SEDIMENT TRANSPORT

1982 ◽  
Vol 1 (18) ◽  
pp. 97
Author(s):  
J. Zacks
Keyword(s):  
Sediment Transport ◽  
Surf Zone ◽  
Survey Techniques ◽  
The Past ◽  
Bed Elevation ◽  
Innovative Methods ◽  
Survey Error ◽  
Nearshore Sediment Transport ◽  
The Many ◽  
The Cost

The cost of many coastal projects is often increased by the expensive beach repair and maintenance required to remedy the destabilising effects of structures on the adjoining coastline. Physical and/or mathematical models have been developed for use in planning these projects in order to predict and quantify the effects of marine sediment transport on the coastal topography. Such models need to be calibrated against prototype data and one method of gauging volumetric sediment movement is by successive bathymetric/ topographic profiting surveys which are performed seasonally and annually. Since large quantities of sediment are related to small changes in bed elevation it is clear that this profiling needs to be done with the utmost precision* The areas most affected extend from the beach through the surf zone to water depths of about 25 metres. The surf zone in particular is a dynamic and hostile area which falls outside the traditional activities of both the hydrographic and land surveyors. Consequently innovative methods, deficient in sound survey principle and practice, have often been pursued in this area without any attempt being made to assess the tolerance on the data. This paper attempts to show that it is possible to produce reliable and verifiable results to the required accuracy by using conventional survey equipment and techniques, also by taking the necessary precautions against the many possible sources of survey error. The procedures and techniques described have evolved from NRIO's involvement over the past decade in major projects at Richards Bay, Durban, Koeberg and in False Bay. The results of a recent verification investigation are fully reported in this paper.

Rapid morphological evolution during beach breaching and closure at a bar-built estuary

2021 ◽  
Author(s):  
Mara Orescanin ◽  
Tyonna McPherson ◽  
Paul Jessen
Keyword(s):  
Sediment Transport ◽  
River Discharge ◽  
Morphological Evolution ◽  
Water Levels ◽  
Low Flow ◽  
Long Term Stability ◽  
Erosion Rates ◽  
Discharge Rates ◽  
Elevation Changes ◽  
Elevated Water

<p>The Carmel River runs 58 km from the Santa Lucia Mountains through the Carmel Valley eventually entering a lagoon at Carmel River State Beach near Carmel, California, USA. During the dry summer months, the lagoon is closed, with no connection to the coastal ocean.  However, during the wet winter months, the river often breaches through the lagoon allowing water to freely flow between the river and Carmel Bay. Sediment transport, in part owing to river discharge and in part owing to ocean forcing (tides and waves), contributes heavily to whether the lagoon is open or closed: when there are low flow conditions, waves and tides can decrease flow rates in the breach, allowing sediment to settle. The sediment budget is expected to be a closed system, owing to the rocky headlands and long-term stability (no yearly regression or transgression) of the shoreline, despite managed attempts to control breach and closure timing. However, it is currently unknown 1) how velocity profiles evolve during breaching, and 2) how much sediment moves during such an event. The hypothesis is that the breach mouth can completely disappear and re-emerge over a single breach-closure cycle, leading to meter-scale daily accretion and erosion rates of berm height if berm elevation is significantly lower than the expected steady-state berm height. Furthermore, it is hypothesized that during active breaching, discharge rates through the breach channel are larger than upstream river discharge rates owing to elevated water levels within the back lagoon. This study uses a RiverSurveyor M9 Acoustic Doppler Profiler to measure outflow discharge and GPS topographic surveys to quantify elevation changes. A velocity profile can be built which will estimate the sediment transport potential within the breach. The information obtained will help identify and better understand the river discharge thresholds which contribute to frequent breaching as well as estimates of morphological evolution during breaching, which are currently unknown, and can assist in determining likelihood of successful managed breaching and closure events. </p>

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