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h2. breakwaters'
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*Background*
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*Research objective*
The main objective of this MSc thesis is the development of universal engineering design criteria that can predict the magnitude of shoreline response to a given design single shore-parallel detached submerged breakwater. These criteria will quantify the formation of a salient/tombolo or erosion as a function of structural, environmental and hydrodynamic parameters.
In order to come up with design criteria for shoreline response to submerged breakwaters this study will be specially focussing on:
• Current literature that is available on submerged breakwaters.
• Modelling of a submerged breakwater with a phase averaging numerical model (Delft3D)
• Sensitivity analysis of the model results to various model characteristics (Morfac, wave-current interaction, mass-flux etc).
• Hydrodynamic and morphologic processes that dominate shoreline response to submerged breakwaters.
• The dependency of the magnitude of shoreline response on principal structural/environmental parameters that govern submerged breakwater induced morphological response.
• Analyses of model results and translation to engineering criteria capable of predicting the magnitude of shoreline response to a design submerged breakwater
*Methodology*
The proposed study can be divided into the following stages:
_Literature review_. First, the hydrodynamic and morphological processes that may affect shoreline response to a submerged breakwater are studied from literature. This theoretical study indicates which are the important processes and corresponding parameters that govern submerged breakwater induced morphological response. In addition, previous studies on submerged breakwaters will be summarised and conclusions are taken into account. This literature study will act as a starting point for this thesis.
_Modelling with of a submerged breakwater with a phase averaging model (Delft3D)_. Second the shoreline response to a submerged breakwater is modelled by a numerical phase averaging model, Delft3D, developed by Deltares. A two-dimensional depth averaged model is set-up to study the important driving processes behind submerged breakwater induced shoreline response, without having the large computational times of a full three-dimensional and phase resolving model. Using an initial alongshore uniform profile and avoiding site-specific conditions will lead to a universal approach so that the eventual design criteria will be applicable world wide.
_Sensitivity analysis numerical parameters_. Applying a numerical model introduces additional (numerical) parameters and assumptions that influence the shoreline response. In order to quantify the influence of these parameters/assumptions and to reduce the computational times, a sensitivity analysis of these parameters is performed.
_Analysis of hydrodynamic and morphologic processes_. From literature most important processes that govern submerged breakwater induced shoreline changes are known. Analysing model results of Delft3D will show whether this phase-averaged and depth averaged model is capable of modelling all the important processes, ignoring detailed turbulence, while using mild slope equations.
_Sunny isle Delft3D calibration case_. Next, measurements from an existing submerged breakwater are used to calibrate the Delft3D model. This field case comprises the Sunny Isle breakwater in Florida USA, a coupled breakwater system containing two detached shore normal submerged breakwaters. Fine tuning of the numerical parameters, together with the sensitivity analyses, will lead to more reliable results when comparing the influence of structural/environmental parameters, while not impairing on computational efficiency of the Delft3D model.
_Structural and environmental parameters_. The next step in this study is the sensitivity analyses on the structural and environmental parameters governing submerged breakwater induced shoreline response. The influence of the most important parameters on shoreline response, followed from the theoretical study, are examined using the model set-up in Delft3D. The results of this analyses, the formation of a salient or erosion, are then quantified and a tendency is searched for.
_Design criteria and comparison_. Using the tendencies of the different parameters, design criteria for submerged breakwater induced shoreline response are made. The final stage of this study will be a comparison between the proposed design criterion and previous studies on submerged breakwater induced shoreline response, followed by conclusions and recommendations for further research.
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Research objective The main objective of this MSc thesis is the development of universal engineering design criteria that can predict the magnitude of shoreline response to a given design single shore-parallel detached submerged breakwater. These criteria will quantify the formation of a salient/tombolo or erosion as a function of structural, environmental and hydrodynamic parameters. In order to come up with design criteria for shoreline response to submerged breakwaters this study will be specially focussing on: • Current literature that is available on submerged breakwaters. • Modelling of a submerged breakwater with a phase averaging numerical model (Delft3D) • Sensitivity analysis of the model results to various model characteristics (Morfac, wave-current interaction, mass-flux etc). • Hydrodynamic and morphologic processes that dominate shoreline response to submerged breakwaters. • The dependency of the magnitude of shoreline response on principal structural/environmental parameters that govern submerged breakwater induced morphological response. • Analyses of model results and translation to engineering criteria capable of predicting the magnitude of shoreline response to a design submerged breakwater Methodology The proposed study can be divided into the following stages: Literature review. First, the hydrodynamic and morphological processes that may affect shoreline response to a submerged breakwater are studied from literature. This theoretical study indicates which are the important processes and corresponding parameters that govern submerged breakwater induced morphological response. In addition, previous studies on submerged breakwaters will be summarised and conclusions are taken into account. This literature study will act as a starting point for this thesis. Modelling with of a submerged breakwater with a phase averaging model (Delft3D). Second the shoreline response to a submerged breakwater is modelled by a numerical phase averaging model, Delft3D, developed by Deltares. A two-dimensional depth averaged model is set-up to study the important driving processes behind submerged breakwater induced shoreline response, without having the large computational times of a full three-dimensional and phase resolving model. Using an initial alongshore uniform profile and avoiding site-specific conditions will lead to a universal approach so that the eventual design criteria will be applicable world wide. Sensitivity analysis numerical parameters. Applying a numerical model introduces additional (numerical) parameters and assumptions that influence the shoreline response. In order to quantify the influence of these parameters/assumptions and to reduce the computational times, a sensitivity analysis of these parameters is performed. Analysis of hydrodynamic and morphologic processes. From literature most important processes that govern submerged breakwater induced shoreline changes are known. Analysing model results of Delft3D will show whether this phase-averaged and depth averaged model is capable of modelling all the important processes, ignoring detailed turbulence, while using mild slope equations. Sunny isle Delft3D calibration case. Next, measurements from an existing submerged breakwater are used to calibrate the Delft3D model. This field case comprises the Sunny Isle breakwater in Florida USA, a coupled breakwater system containing two detached shore normal submerged breakwaters. Fine tuning of the numerical parameters, together with the sensitivity analyses, will lead to more reliable results when comparing the influence of structural/environmental parameters, while not impairing on computational efficiency of the Delft3D model. Structural and environmental parameters. The next step in this study is the sensitivity analyses on the structural and environmental parameters governing submerged breakwater induced shoreline response. The influence of the most important parameters on shoreline response, followed from the theoretical study, are examined using the model set-up in Delft3D. The results of this analyses, the formation of a salient or erosion, are then quantified and a tendency is searched for. Design criteria and comparison. Using the tendencies of the different parameters, design criteria for submerged breakwater induced shoreline response are made. The final stage of this study will be a comparison between the proposed design criterion and previous studies on submerged breakwater induced shoreline response, followed by conclusions and recommendations for further research. |
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|| Name | Roland Vlijm||
|| Email | Roland.vlijm@Deltares.nl ||
|| Room | HH 1.17 ||
|| Software package | Delft3D ||
|| Start Date | Nov 2010 ||
|| Specialisation Programme | Coastal Engineering ||
|| Deltares supervisors | Arjen Luijendijk ||
|| | Rosh Ranasinghe ||
|| TU Delft professor | Prof. Marcel Stive||
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