The vertical tide in the Sea Scheldt (Belgium) is predicted using a combination of harmonic tidal prediction and 1D hydraulic modeling. At Prosperpolder (a measurement station close to the Dutch-Belgian border), four ...The vertical tide in the Sea Scheldt (Belgium) is predicted using a combination of harmonic tidal prediction and 1D hydraulic modeling. At Prosperpolder (a measurement station close to the Dutch-Belgian border), four years of water level data (2009-2012) are analyzed to obtain the harmonic components at that location. The accuracy of the harmonic prediction is checked with a statistical analysis of an astronomical hindcast for 2009-2012 against measurements. An existing 1D hydraulic model of the tidally influenced part of the Scheldt estuary is cut off at Prosperpolder. The time series of tidally predicted water levels at Prosperpolder is used as a downstream boundary condition for the hydraulic model. In this way, a tidal prediction can be obtained for any location in the Sea Scheldt, also for locations where no harmonic components are available, whilst guaranteeing the consistency between the predicted time series.展开更多
The KCS Container Ship executing zigzag and turning circle maneuvers in shallow water is studied numerically with CFD simulation.Different factors affecting the accuracy of the numerical prediction such as grid densit...The KCS Container Ship executing zigzag and turning circle maneuvers in shallow water is studied numerically with CFD simulation.Different factors affecting the accuracy of the numerical prediction such as grid density,overset discretization,propeller model,turbulence modeling and setup condition have been carefully investigated.Numerical predictions for port side and starboard side turning circle maneuvers and 3 different zigzag maneuvers are compared with experimental data obtained by Flanders Hydraulics(FH)for the KCS ship model at scale 1/52.66 with Froude number Fr=0.095 and water depth to draft ratio h/T=1.2 in tank conditions.To better assess the accuracy of the numerical prediction,simulations have been performed both with a non-confined and confined configuration.展开更多
The open-source code DualSPHysics is used in this work to compute the wave run-up in an existing dike in the Chinese coast using realistic dimensions, bathymetry and wave conditions. The GPU computing power of the Dua...The open-source code DualSPHysics is used in this work to compute the wave run-up in an existing dike in the Chinese coast using realistic dimensions, bathymetry and wave conditions. The GPU computing power of the DualSPHysics allows simulating real-engineering problems that involve complex geometries with a high resolution in a reasonable computational time. The code is first validated by comparing the numerical free-surface elevation, the wave orbital velocities and the time series of the run-up with physical data in a wave flume. Those experiments include a smooth dike and an armored dike with two layers of cubic blocks. After validation,the code is applied to a real case to obtain the wave run-up under different incident wave conditions. In order to simulate the real open sea, the spurious reflections from the wavemaker are removed by using an active wave absorption technique.展开更多
Ships sailing in shallow and/or confined water(when calling a harbour or other berthing areas),will experience a different behaviour due to the interaction with vertical and/or horizontal boundaries.Among other hydrod...Ships sailing in shallow and/or confined water(when calling a harbour or other berthing areas),will experience a different behaviour due to the interaction with vertical and/or horizontal boundaries.Among other hydrodynamic changes induced in confined water,the lateral ship-bank interaction force changes its sign at a critical distance between ship and bank or bottom.However,this distance and its effects on model test results have not been quantified in the past.To investigate the shallow water hydrodynamics coupled with bank effects,systematic model tests were carried out at Flanders Hydraulics Research(FHR)with different ship models.The following parameters were systematically varied:water depth,lateral position,speed,and propeller rate.The change of the ship-bank induced lateral force from an attraction force in medium-deep and shallow water to a repulsion force in extremely shallow water conditions,can be ascribed to the interaction of the boundary layers of the ship model and the environment(tank and installed banks).In this article,a mathematical model is proposed for the critical distance in terms of boundary layer influence thickness.This indicates the range where the model tests are influenced by the horizontal or vertical restrictions combined with the propeller’s dynamic effects.Moreover,the expression has also been extended to describe the relationship between full-scale ship length and water depth with the boundary layer influence thickness.Due to lower Reynolds numbers and relatively thicker boundary layers at model scale,upscaling of the model test results,according to Froude’s law,may provide erroneous results.The influence of the boundary layer initiates at a relatively higher under keel clearance(UKC)for a smaller ship model compared with a larger ship model.Therefore,the boundary layer’s influence with respect to ship model length should be considered during model testing.展开更多
Breaching flow occurs during the breach development of the embankment, dike, earthen dam, landslide barrier, etc. and plays an import role in the breaching erosion as the driving force. According to the previous resea...Breaching flow occurs during the breach development of the embankment, dike, earthen dam, landslide barrier, etc. and plays an import role in the breaching erosion as the driving force. According to the previous research, the breaching process can be classified into initiation phase, breach widening phase and breach deepening phase. Based on the breaching development classifications, the breaching flow can be seen as a special compound weir flow when the breach channel is in the relatively equilibrium condition. There were five physical flow models were designed in the hypothesis of rectangular shape and trapezoidal shape for the breach channel cross sections to study the breaching flow characteristics. The distributions of water level and velocity were measured and analysed in the breaching flows in overtopping condition and emerged condition. There were two helicoidal flows above the breach channel slopes and triangular hydraulic jump in the downstream of the breach channel in the overtopping condition and emerged condition. The hydraulic energy loss was calculated according to the breaching velocity and water level distribution in the upstream and downstream of the model. It is found that the test results of the breach flow physical model can be valuable to bring insight of the breaching process of embankment and make contributions to the validations and verifications of breach numerical models.展开更多
文摘The vertical tide in the Sea Scheldt (Belgium) is predicted using a combination of harmonic tidal prediction and 1D hydraulic modeling. At Prosperpolder (a measurement station close to the Dutch-Belgian border), four years of water level data (2009-2012) are analyzed to obtain the harmonic components at that location. The accuracy of the harmonic prediction is checked with a statistical analysis of an astronomical hindcast for 2009-2012 against measurements. An existing 1D hydraulic model of the tidally influenced part of the Scheldt estuary is cut off at Prosperpolder. The time series of tidally predicted water levels at Prosperpolder is used as a downstream boundary condition for the hydraulic model. In this way, a tidal prediction can be obtained for any location in the Sea Scheldt, also for locations where no harmonic components are available, whilst guaranteeing the consistency between the predicted time series.
文摘The KCS Container Ship executing zigzag and turning circle maneuvers in shallow water is studied numerically with CFD simulation.Different factors affecting the accuracy of the numerical prediction such as grid density,overset discretization,propeller model,turbulence modeling and setup condition have been carefully investigated.Numerical predictions for port side and starboard side turning circle maneuvers and 3 different zigzag maneuvers are compared with experimental data obtained by Flanders Hydraulics(FH)for the KCS ship model at scale 1/52.66 with Froude number Fr=0.095 and water depth to draft ratio h/T=1.2 in tank conditions.To better assess the accuracy of the numerical prediction,simulations have been performed both with a non-confined and confined configuration.
基金Project supported by the National Key R&D Program of China(Grant No.2017YFC1404801)
文摘The open-source code DualSPHysics is used in this work to compute the wave run-up in an existing dike in the Chinese coast using realistic dimensions, bathymetry and wave conditions. The GPU computing power of the DualSPHysics allows simulating real-engineering problems that involve complex geometries with a high resolution in a reasonable computational time. The code is first validated by comparing the numerical free-surface elevation, the wave orbital velocities and the time series of the run-up with physical data in a wave flume. Those experiments include a smooth dike and an armored dike with two layers of cubic blocks. After validation,the code is applied to a real case to obtain the wave run-up under different incident wave conditions. In order to simulate the real open sea, the spurious reflections from the wavemaker are removed by using an active wave absorption technique.
文摘Ships sailing in shallow and/or confined water(when calling a harbour or other berthing areas),will experience a different behaviour due to the interaction with vertical and/or horizontal boundaries.Among other hydrodynamic changes induced in confined water,the lateral ship-bank interaction force changes its sign at a critical distance between ship and bank or bottom.However,this distance and its effects on model test results have not been quantified in the past.To investigate the shallow water hydrodynamics coupled with bank effects,systematic model tests were carried out at Flanders Hydraulics Research(FHR)with different ship models.The following parameters were systematically varied:water depth,lateral position,speed,and propeller rate.The change of the ship-bank induced lateral force from an attraction force in medium-deep and shallow water to a repulsion force in extremely shallow water conditions,can be ascribed to the interaction of the boundary layers of the ship model and the environment(tank and installed banks).In this article,a mathematical model is proposed for the critical distance in terms of boundary layer influence thickness.This indicates the range where the model tests are influenced by the horizontal or vertical restrictions combined with the propeller’s dynamic effects.Moreover,the expression has also been extended to describe the relationship between full-scale ship length and water depth with the boundary layer influence thickness.Due to lower Reynolds numbers and relatively thicker boundary layers at model scale,upscaling of the model test results,according to Froude’s law,may provide erroneous results.The influence of the boundary layer initiates at a relatively higher under keel clearance(UKC)for a smaller ship model compared with a larger ship model.Therefore,the boundary layer’s influence with respect to ship model length should be considered during model testing.
文摘Breaching flow occurs during the breach development of the embankment, dike, earthen dam, landslide barrier, etc. and plays an import role in the breaching erosion as the driving force. According to the previous research, the breaching process can be classified into initiation phase, breach widening phase and breach deepening phase. Based on the breaching development classifications, the breaching flow can be seen as a special compound weir flow when the breach channel is in the relatively equilibrium condition. There were five physical flow models were designed in the hypothesis of rectangular shape and trapezoidal shape for the breach channel cross sections to study the breaching flow characteristics. The distributions of water level and velocity were measured and analysed in the breaching flows in overtopping condition and emerged condition. There were two helicoidal flows above the breach channel slopes and triangular hydraulic jump in the downstream of the breach channel in the overtopping condition and emerged condition. The hydraulic energy loss was calculated according to the breaching velocity and water level distribution in the upstream and downstream of the model. It is found that the test results of the breach flow physical model can be valuable to bring insight of the breaching process of embankment and make contributions to the validations and verifications of breach numerical models.
