Shoreline change analysis frequently begins with feature identification through visual interpretation(proxy-based shoreline)or the intersection of a specific tidal zone(datum-based shoreline).Using proxy-based shoreli...Shoreline change analysis frequently begins with feature identification through visual interpretation(proxy-based shoreline)or the intersection of a specific tidal zone(datum-based shoreline).Using proxy-based shoreline information,this study quantifies the distance between proxy-based and datum-based shoreline data,which is defined as the proxydatum bias.The study was conducted at meso-tidal beaches in Kuala Nerus,Terengganu,Malaysia,with morphodynamic responses to northeast and southwest monsoons.The high-water line(HWL)shoreline(proxy-based)was determined using ortho-rectified aerial images captured by an unmanned aerial vehicle(UAV).By contrast,the mean high-water(MHW)shoreline(datum-based)was determined using measured beach profiles adjusted with the Peninsular Malaysia Geodetic Vertical Datum(DTGSM).The theoretical proxy-datum bias was approximated using the best estimate(median)for the beach slope,wave height,and wave period from the estimated total water level(TWL)model.Based on the study,the recorded horizontal proxy-datum bias for the research area was up to 32 m.This study also discovered that the theoretical assumption of the proxy-datum bias based on the TWL model yields values comparable to those of the measurements,with a narrower distinction in bias for steeper beach slopes than the obtained results.The determined proxydatum bias value can benefit future shoreline change studies as it could be incorporated to either proxy-based shorelines by shifting the shoreline seaward or to datum-based shorelines by shifting the shoreline landward in order of the bias value.The seasonal monsoon’s effect on beach profiles should be considered when calculating bias values and conducting potential shoreline change rate studies.展开更多
In many cases of wave structure interactions,three-dimensional models are used to demonstrate real-life complex environ-ments in large domain scales.In the seakeeping context,predicting the motion responses in the int...In many cases of wave structure interactions,three-dimensional models are used to demonstrate real-life complex environ-ments in large domain scales.In the seakeeping context,predicting the motion responses in the interaction of a long body resembling a ship structure with regular waves is crucial and can be challenging.In this work,regular waves interacting with a rigid foating structure were simulated using the open-source code based on the weakly compressible smoothed par-ticle hydrodynamics(WCSPH)method,and optimal parameters were suggested for diferent wave environments.Vertical displacements were computed,and their response amplitude operators(RAOs)were found to be in good agreement with experimental,numerical,and analytical results.Discrepancies of numerical and experimental RAOs tended to increase at low wave frequencies,particularly at amidships and near the bow.In addition,the instantaneous wave contours of the sur-rounding model were examined to reveal the efects of localized waves along the structure and wave dissipation.The results indicated that the motion response from the WCSPH responds well at the highest frequency range(ω>5.235 rad/s).展开更多
基金Supported by the Internal Grant of Universiti Malaysia Terengganu under the Translational Research Grant No.Vot 53464.
文摘Shoreline change analysis frequently begins with feature identification through visual interpretation(proxy-based shoreline)or the intersection of a specific tidal zone(datum-based shoreline).Using proxy-based shoreline information,this study quantifies the distance between proxy-based and datum-based shoreline data,which is defined as the proxydatum bias.The study was conducted at meso-tidal beaches in Kuala Nerus,Terengganu,Malaysia,with morphodynamic responses to northeast and southwest monsoons.The high-water line(HWL)shoreline(proxy-based)was determined using ortho-rectified aerial images captured by an unmanned aerial vehicle(UAV).By contrast,the mean high-water(MHW)shoreline(datum-based)was determined using measured beach profiles adjusted with the Peninsular Malaysia Geodetic Vertical Datum(DTGSM).The theoretical proxy-datum bias was approximated using the best estimate(median)for the beach slope,wave height,and wave period from the estimated total water level(TWL)model.Based on the study,the recorded horizontal proxy-datum bias for the research area was up to 32 m.This study also discovered that the theoretical assumption of the proxy-datum bias based on the TWL model yields values comparable to those of the measurements,with a narrower distinction in bias for steeper beach slopes than the obtained results.The determined proxydatum bias value can benefit future shoreline change studies as it could be incorporated to either proxy-based shorelines by shifting the shoreline seaward or to datum-based shorelines by shifting the shoreline landward in order of the bias value.The seasonal monsoon’s effect on beach profiles should be considered when calculating bias values and conducting potential shoreline change rate studies.
基金the Ministry of Higher Education(MOHE)of Malaysia under the Long Term Research Grant Scheme(LRGS)No.LRGS21-001–0005 and LRGS/1/2020/UMT/01/1/4.
文摘In many cases of wave structure interactions,three-dimensional models are used to demonstrate real-life complex environ-ments in large domain scales.In the seakeeping context,predicting the motion responses in the interaction of a long body resembling a ship structure with regular waves is crucial and can be challenging.In this work,regular waves interacting with a rigid foating structure were simulated using the open-source code based on the weakly compressible smoothed par-ticle hydrodynamics(WCSPH)method,and optimal parameters were suggested for diferent wave environments.Vertical displacements were computed,and their response amplitude operators(RAOs)were found to be in good agreement with experimental,numerical,and analytical results.Discrepancies of numerical and experimental RAOs tended to increase at low wave frequencies,particularly at amidships and near the bow.In addition,the instantaneous wave contours of the sur-rounding model were examined to reveal the efects of localized waves along the structure and wave dissipation.The results indicated that the motion response from the WCSPH responds well at the highest frequency range(ω>5.235 rad/s).
