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Erik Toorman - One of the best experts on this subject based on the ideXlab platform.
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A parameter model for dredge plume sediment source terms
Ocean Dynamics, 2017Co-Authors: Boudewijn Decrop, T. De Mulder, Erik ToormanAbstract:The presented model allows for fast simulations of the near-field behaviour of overflow dredging plumes. Overflow dredging plumes occur when dredging vessels employ a dropshaft release system to discharge the excess sea water, which is pumped into the trailing suction hopper dredger (TSHD) along with the dredged sediments. The fine sediment frAction in the loaded water-sediment mixture does not fully settle before it reaches the overflow shaft. By consequence, the released water contains a fine sediment frAction of time-varying concentration. The sediment grain size is in the range of clays, silt and fine sand; the sediment concentration varies roughly between 10 and 200 g/l in most cases, peaking at even higher value with short duration. In order to assess the environmental impact of the increased turbidity caused by this release, plume dispersion predictions are often carried out. These predictions are usually executed with a large-scale model covering a complete coastal zone, bay, or estuary. A source term of fine sediments is implemented in the hydrodynamic model to simulate the fine sediment dispersion. The large-scale model mesh resolution and governing equations, however, do not allow to simulate the near-field plume behaviour in the vicinity of the ship hull and Propellers. Moreover, in the near-field, these plumes are under influence of buoyancy forces and air bubbles. The initial distribution of sediments is therefore unknown and has to be based on crude assumptions at present. The initial (vertical) distribution of the sediment source is indeed of great influence on the final far-field plume dispersion results. In order to study this near-field behaviour, a highly-detailed computationally fluid dynamics (CFD) model was developed. This model contains a realistic geometry of a dredging vessel, buoyancy effects, air bubbles and Propeller Action, and was validated earlier by comparing with field measurements. A CFD model requires significant simulation times, which is not available in all situations. For example, to allow correct representation of overflow plume dispersion in a real-time forecasting model, a fast assessment of the near-field behaviour is needed. For this reason, a semi-analytical parameter model has been developed that reproduces the near-field sediment dispersion obtained with the CFD model in a relatively accurate way. In this paper, this so-called grey-box model is presented.
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Large-eddy simulations of a sediment plume released by a dredger using overflow
Journal of Applied Water Engineering and Research, 2016Co-Authors: Boudewijn Decrop, Marc Sas, T. De Mulder, Erik ToormanAbstract:Sediment plume predictions are part of the assessment of environmental impacts of dredging. The main source of turbidity while employing Trailer Suction Hopper Dredgers is the release of excess water through the overflow shaft. The near-field plume dynamics below and directly behind the sailing hopper dredgers are traditionally unknown during predictions of far-field plume dispersion. Indeed, an accurate input of the vertical and horizontal distributions of sediment at the source location is important to obtain reliable results at environmentally sensitive areas further away. In this paper, a computational fluid dynamics model is presented as a tool to determine the three-dimensional flows of water, sediment and air bubbles directly after release from the overflow shaft. The full dredger hull geometry and an actuator disc accounting for Propeller Action are included. It is shown that the model can reproduce two different cases of overflow plumes measured in the field with fair accuracy.
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Large-Eddy simulations of a sediment-laden Buoyant jet resulting from Dredgers using overflow
2014Co-Authors: Boudewijn Decrop, Marc Sas, T. De Mulder, Erik ToormanAbstract:Turbidity plumes are an important topic in the environmental aspects of dredging. The main source of turbidity while employing Trailer Suction Hopper Dredgers is the release of excess water through the overflow shaft. In order to minimise environmental impacts of turbidity in early stages of planning as well as during project execution, turbidity prediction tools are necessary. To this end, numerical modelling tools are the most effective in the prediction of the sea currents and sediment dispersion. The near field plume dynamics below and directly behind the sailing hopper dredgers has always been the weakest link in these predictions, since accurate input of the vertical and horizontal distributions of sediment at the source location are paramount to obtain reliable results at the environmentally sensitive areas further away. In this paper, a Computational Fluid Dynamics model is presented as a tool to determine the three-dimensional flows of water, sediment and air bubbles directly after release from the overflow shaft. A full dredger hull geometry and an actuator disk accounting for Propeller Action add to the representation of the complexity of the flow. It is shown that the model can reproduce two different cases of overflow plumes measured in the field with fair accuracy.
Boudewijn Decrop - One of the best experts on this subject based on the ideXlab platform.
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A parameter model for dredge plume sediment source terms
Ocean Dynamics, 2017Co-Authors: Boudewijn Decrop, T. De Mulder, Erik ToormanAbstract:The presented model allows for fast simulations of the near-field behaviour of overflow dredging plumes. Overflow dredging plumes occur when dredging vessels employ a dropshaft release system to discharge the excess sea water, which is pumped into the trailing suction hopper dredger (TSHD) along with the dredged sediments. The fine sediment frAction in the loaded water-sediment mixture does not fully settle before it reaches the overflow shaft. By consequence, the released water contains a fine sediment frAction of time-varying concentration. The sediment grain size is in the range of clays, silt and fine sand; the sediment concentration varies roughly between 10 and 200 g/l in most cases, peaking at even higher value with short duration. In order to assess the environmental impact of the increased turbidity caused by this release, plume dispersion predictions are often carried out. These predictions are usually executed with a large-scale model covering a complete coastal zone, bay, or estuary. A source term of fine sediments is implemented in the hydrodynamic model to simulate the fine sediment dispersion. The large-scale model mesh resolution and governing equations, however, do not allow to simulate the near-field plume behaviour in the vicinity of the ship hull and Propellers. Moreover, in the near-field, these plumes are under influence of buoyancy forces and air bubbles. The initial distribution of sediments is therefore unknown and has to be based on crude assumptions at present. The initial (vertical) distribution of the sediment source is indeed of great influence on the final far-field plume dispersion results. In order to study this near-field behaviour, a highly-detailed computationally fluid dynamics (CFD) model was developed. This model contains a realistic geometry of a dredging vessel, buoyancy effects, air bubbles and Propeller Action, and was validated earlier by comparing with field measurements. A CFD model requires significant simulation times, which is not available in all situations. For example, to allow correct representation of overflow plume dispersion in a real-time forecasting model, a fast assessment of the near-field behaviour is needed. For this reason, a semi-analytical parameter model has been developed that reproduces the near-field sediment dispersion obtained with the CFD model in a relatively accurate way. In this paper, this so-called grey-box model is presented.
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Large-eddy simulations of a sediment plume released by a dredger using overflow
Journal of Applied Water Engineering and Research, 2016Co-Authors: Boudewijn Decrop, Marc Sas, T. De Mulder, Erik ToormanAbstract:Sediment plume predictions are part of the assessment of environmental impacts of dredging. The main source of turbidity while employing Trailer Suction Hopper Dredgers is the release of excess water through the overflow shaft. The near-field plume dynamics below and directly behind the sailing hopper dredgers are traditionally unknown during predictions of far-field plume dispersion. Indeed, an accurate input of the vertical and horizontal distributions of sediment at the source location is important to obtain reliable results at environmentally sensitive areas further away. In this paper, a computational fluid dynamics model is presented as a tool to determine the three-dimensional flows of water, sediment and air bubbles directly after release from the overflow shaft. The full dredger hull geometry and an actuator disc accounting for Propeller Action are included. It is shown that the model can reproduce two different cases of overflow plumes measured in the field with fair accuracy.
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Large-Eddy simulations of a sediment-laden Buoyant jet resulting from Dredgers using overflow
2014Co-Authors: Boudewijn Decrop, Marc Sas, T. De Mulder, Erik ToormanAbstract:Turbidity plumes are an important topic in the environmental aspects of dredging. The main source of turbidity while employing Trailer Suction Hopper Dredgers is the release of excess water through the overflow shaft. In order to minimise environmental impacts of turbidity in early stages of planning as well as during project execution, turbidity prediction tools are necessary. To this end, numerical modelling tools are the most effective in the prediction of the sea currents and sediment dispersion. The near field plume dynamics below and directly behind the sailing hopper dredgers has always been the weakest link in these predictions, since accurate input of the vertical and horizontal distributions of sediment at the source location are paramount to obtain reliable results at the environmentally sensitive areas further away. In this paper, a Computational Fluid Dynamics model is presented as a tool to determine the three-dimensional flows of water, sediment and air bubbles directly after release from the overflow shaft. A full dredger hull geometry and an actuator disk accounting for Propeller Action add to the representation of the complexity of the flow. It is shown that the model can reproduce two different cases of overflow plumes measured in the field with fair accuracy.
T. De Mulder - One of the best experts on this subject based on the ideXlab platform.
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A parameter model for dredge plume sediment source terms
Ocean Dynamics, 2017Co-Authors: Boudewijn Decrop, T. De Mulder, Erik ToormanAbstract:The presented model allows for fast simulations of the near-field behaviour of overflow dredging plumes. Overflow dredging plumes occur when dredging vessels employ a dropshaft release system to discharge the excess sea water, which is pumped into the trailing suction hopper dredger (TSHD) along with the dredged sediments. The fine sediment frAction in the loaded water-sediment mixture does not fully settle before it reaches the overflow shaft. By consequence, the released water contains a fine sediment frAction of time-varying concentration. The sediment grain size is in the range of clays, silt and fine sand; the sediment concentration varies roughly between 10 and 200 g/l in most cases, peaking at even higher value with short duration. In order to assess the environmental impact of the increased turbidity caused by this release, plume dispersion predictions are often carried out. These predictions are usually executed with a large-scale model covering a complete coastal zone, bay, or estuary. A source term of fine sediments is implemented in the hydrodynamic model to simulate the fine sediment dispersion. The large-scale model mesh resolution and governing equations, however, do not allow to simulate the near-field plume behaviour in the vicinity of the ship hull and Propellers. Moreover, in the near-field, these plumes are under influence of buoyancy forces and air bubbles. The initial distribution of sediments is therefore unknown and has to be based on crude assumptions at present. The initial (vertical) distribution of the sediment source is indeed of great influence on the final far-field plume dispersion results. In order to study this near-field behaviour, a highly-detailed computationally fluid dynamics (CFD) model was developed. This model contains a realistic geometry of a dredging vessel, buoyancy effects, air bubbles and Propeller Action, and was validated earlier by comparing with field measurements. A CFD model requires significant simulation times, which is not available in all situations. For example, to allow correct representation of overflow plume dispersion in a real-time forecasting model, a fast assessment of the near-field behaviour is needed. For this reason, a semi-analytical parameter model has been developed that reproduces the near-field sediment dispersion obtained with the CFD model in a relatively accurate way. In this paper, this so-called grey-box model is presented.
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Large-eddy simulations of a sediment plume released by a dredger using overflow
Journal of Applied Water Engineering and Research, 2016Co-Authors: Boudewijn Decrop, Marc Sas, T. De Mulder, Erik ToormanAbstract:Sediment plume predictions are part of the assessment of environmental impacts of dredging. The main source of turbidity while employing Trailer Suction Hopper Dredgers is the release of excess water through the overflow shaft. The near-field plume dynamics below and directly behind the sailing hopper dredgers are traditionally unknown during predictions of far-field plume dispersion. Indeed, an accurate input of the vertical and horizontal distributions of sediment at the source location is important to obtain reliable results at environmentally sensitive areas further away. In this paper, a computational fluid dynamics model is presented as a tool to determine the three-dimensional flows of water, sediment and air bubbles directly after release from the overflow shaft. The full dredger hull geometry and an actuator disc accounting for Propeller Action are included. It is shown that the model can reproduce two different cases of overflow plumes measured in the field with fair accuracy.
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Large-Eddy simulations of a sediment-laden Buoyant jet resulting from Dredgers using overflow
2014Co-Authors: Boudewijn Decrop, Marc Sas, T. De Mulder, Erik ToormanAbstract:Turbidity plumes are an important topic in the environmental aspects of dredging. The main source of turbidity while employing Trailer Suction Hopper Dredgers is the release of excess water through the overflow shaft. In order to minimise environmental impacts of turbidity in early stages of planning as well as during project execution, turbidity prediction tools are necessary. To this end, numerical modelling tools are the most effective in the prediction of the sea currents and sediment dispersion. The near field plume dynamics below and directly behind the sailing hopper dredgers has always been the weakest link in these predictions, since accurate input of the vertical and horizontal distributions of sediment at the source location are paramount to obtain reliable results at the environmentally sensitive areas further away. In this paper, a Computational Fluid Dynamics model is presented as a tool to determine the three-dimensional flows of water, sediment and air bubbles directly after release from the overflow shaft. A full dredger hull geometry and an actuator disk accounting for Propeller Action add to the representation of the complexity of the flow. It is shown that the model can reproduce two different cases of overflow plumes measured in the field with fair accuracy.
Sas Marc - One of the best experts on this subject based on the ideXlab platform.
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Large-eddy simulations of a sediment plume released by a dredger using overflow
Taylor & Francis, 2018Co-Authors: Decrop Oudewij, Sas Marc, De Mulde Tom, Toorman, Erik A.Abstract:Sediment plume predictions are part of the assessment of environmental impacts of dredging. The main source of turbidity while employing Trailer Suction Hopper Dredgers is the release of excess water through the overflow shaft. The near-field plume dynamics below and directly behind the sailing hopper dredgers are traditionally unknown during predictions of far-field plume dispersion. Indeed, an accurate input of the vertical and horizontal distributions of sediment at the source location is important to obtain reliable results at environmentally sensitive areas further away. In this paper, a computational fluid dynamics model is presented as a tool to determine the three-dimensional flows of water, sediment and air bubbles directly after release from the overflow shaft. The full dredger hull geometry and an actuator disc accounting for Propeller Action are included. It is shown that the model can reproduce two different cases of overflow plumes measured in the field with fair accuracy.status: publishe
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A parameter model for dredge plume sediment source terms
'Springer Science and Business Media LLC', 2017Co-Authors: Decrop Oudewij, De Mulde Tom, Toorma Erik, Sas MarcAbstract:© 2016, Springer-Verlag Berlin Heidelberg. The presented model allows for fast simulations of the near-field behaviour of overflow dredging plumes. Overflow dredging plumes occur when dredging vessels employ a dropshaft release system to discharge the excess sea water, which is pumped into the trailing suction hopper dredger (TSHD) along with the dredged sediments. The fine sediment frAction in the loaded water-sediment mixture does not fully settle before it reaches the overflow shaft. By consequence, the released water contains a fine sediment frAction of time-varying concentration. The sediment grain size is in the range of clays, silt and fine sand; the sediment concentration varies roughly between 10 and 200 g/l in most cases, peaking at even higher value with short duration. In order to assess the environmental impact of the increased turbidity caused by this release, plume dispersion predictions are often carried out. These predictions are usually executed with a large-scale model covering a complete coastal zone, bay, or estuary. A source term of fine sediments is implemented in the hydrodynamic model to simulate the fine sediment dispersion. The large-scale model mesh resolution and governing equations, however, do not allow to simulate the near-field plume behaviour in the vicinity of the ship hull and Propellers. Moreover, in the near-field, these plumes are under influence of buoyancy forces and air bubbles. The initial distribution of sediments is therefore unknown and has to be based on crude assumptions at present. The initial (vertical) distribution of the sediment source is indeed of great influence on the final far-field plume dispersion results. In order to study this near-field behaviour, a highly-detailed computationally fluid dynamics (CFD) model was developed. This model contains a realistic geometry of a dredging vessel, buoyancy effects, air bubbles and Propeller Action, and was validated earlier by comparing with field measurements. A CFD model requires significant simulation times, which is not available in all situations. For example, to allow correct representation of overflow plume dispersion in a real-time forecasting model, a fast assessment of the near-field behaviour is needed. For this reason, a semi-analytical parameter model has been developed that reproduces the near-field sediment dispersion obtained with the CFD model in a relatively accurate way. In this paper, this so-called grey-box model is presented.status: publishe
Decrop Oudewij - One of the best experts on this subject based on the ideXlab platform.
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Large-eddy simulations of a sediment plume released by a dredger using overflow
Taylor & Francis, 2018Co-Authors: Decrop Oudewij, Sas Marc, De Mulde Tom, Toorman, Erik A.Abstract:Sediment plume predictions are part of the assessment of environmental impacts of dredging. The main source of turbidity while employing Trailer Suction Hopper Dredgers is the release of excess water through the overflow shaft. The near-field plume dynamics below and directly behind the sailing hopper dredgers are traditionally unknown during predictions of far-field plume dispersion. Indeed, an accurate input of the vertical and horizontal distributions of sediment at the source location is important to obtain reliable results at environmentally sensitive areas further away. In this paper, a computational fluid dynamics model is presented as a tool to determine the three-dimensional flows of water, sediment and air bubbles directly after release from the overflow shaft. The full dredger hull geometry and an actuator disc accounting for Propeller Action are included. It is shown that the model can reproduce two different cases of overflow plumes measured in the field with fair accuracy.status: publishe
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A parameter model for dredge plume sediment source terms
'Springer Science and Business Media LLC', 2017Co-Authors: Decrop Oudewij, De Mulde Tom, Toorma Erik, Sas MarcAbstract:© 2016, Springer-Verlag Berlin Heidelberg. The presented model allows for fast simulations of the near-field behaviour of overflow dredging plumes. Overflow dredging plumes occur when dredging vessels employ a dropshaft release system to discharge the excess sea water, which is pumped into the trailing suction hopper dredger (TSHD) along with the dredged sediments. The fine sediment frAction in the loaded water-sediment mixture does not fully settle before it reaches the overflow shaft. By consequence, the released water contains a fine sediment frAction of time-varying concentration. The sediment grain size is in the range of clays, silt and fine sand; the sediment concentration varies roughly between 10 and 200 g/l in most cases, peaking at even higher value with short duration. In order to assess the environmental impact of the increased turbidity caused by this release, plume dispersion predictions are often carried out. These predictions are usually executed with a large-scale model covering a complete coastal zone, bay, or estuary. A source term of fine sediments is implemented in the hydrodynamic model to simulate the fine sediment dispersion. The large-scale model mesh resolution and governing equations, however, do not allow to simulate the near-field plume behaviour in the vicinity of the ship hull and Propellers. Moreover, in the near-field, these plumes are under influence of buoyancy forces and air bubbles. The initial distribution of sediments is therefore unknown and has to be based on crude assumptions at present. The initial (vertical) distribution of the sediment source is indeed of great influence on the final far-field plume dispersion results. In order to study this near-field behaviour, a highly-detailed computationally fluid dynamics (CFD) model was developed. This model contains a realistic geometry of a dredging vessel, buoyancy effects, air bubbles and Propeller Action, and was validated earlier by comparing with field measurements. A CFD model requires significant simulation times, which is not available in all situations. For example, to allow correct representation of overflow plume dispersion in a real-time forecasting model, a fast assessment of the near-field behaviour is needed. For this reason, a semi-analytical parameter model has been developed that reproduces the near-field sediment dispersion obtained with the CFD model in a relatively accurate way. In this paper, this so-called grey-box model is presented.status: publishe
