Development Of Discontinuous Galerkin Model For Three-dimensional Hydrodynamic And Sediment Transport In Estuarine And Coastal Environment

Three-dimensional (3D) numerical models, as important approaches fordescribing hydrodynamic and sediment transport in the complex situations, areplaying increasingly important roles in solving engineering sediment problems ofestuatine and coastal environment. A discontinuous Gaelerkin model for3Dhydrodynamic and suspended sediment transport in estuarine and coastal environmentwas developed and further validated through analytical solutions and experimentaldatas. The model was applied for simulation of hydrodynamic and suspendedsediment motion around Huanghua Harbor, and sediment transport and channelsiltation were investigated. The main conlusions are summarized as follows.(1) Based on a new type numerical method, the discontinuous Galerkin method,a3D hydrodynamic model for combined waves and current was developed, in whichthe3D radiation stresses, as well as the effect of surface roller, wave-inducedturbulence mixing and bottom shear stresses due to combined waves and current, wasincorporated. The model was applied to numerical simulation of some classicexamples, and the simulated results agree with the analytical solutions andexperimental datas satisfactorily.(2) Based on the discontinuous Galerkin method, a second-order3D suspendedsediment transport model under waves and current was developed. In the model, theslope limiter was used in order to alleviate spurious oscillations near discontinuitiesand enhance the stability and the ability to capture concentration discontinuity.Vertical diffusion coefficients for different hydrodynamic conditions of pure current,pure wave, wave breaking and combined waves and current, were introduced in thesuspended sediment transport model, as well as the damping of turbulent due to thepresence of high sediment concentrations. The established model was tested andvalidated by typical analytical solutions and experimental datas.(3) The simulated results of tidal current, suspended sediment concentration,waves during windy days, and channel siltation were compared with the observed dataaround Huanghua Harbor. It is shown that the proposed model can reasonablydescribe the hydrodynamic and sediment motion in real coastal environment, and can be applied to engineering issues. The multi-fraction sediment module in the proposedmodel can reasonably describe the variation of median diameter of deposited sedimentalong the channel.(4) Taking the coast around Huanghua Harbor as a typical silty coast, numericalexperiments were set up to investigate the hydrodynamic and sediment motion atdifferent wind conditions in silty coast. Simulated results showed that the strongwaves due to strong winds are the main factors for forming the high concentratedsuspensions near the bed. The high concentrated sediment suspension near the bottomwill appear on both sides of channel in a large sea area due to the shorewards winds ofBeaufort force8. Furthermore, the nonequilibrium transport of high concentratedsuspensions near-bottom will result in the severe channel siltation.