Numerical Simulation Of Storm Surges In The Bohai Sea

The bohai sea,as Chinese inland sea,has a vast coastline,with plenty of coastal cities and residents,and there are rich resources of harbor and marine industry.In history,bohai sea were always attacked by storm surges all over the year,and bohai sea is one of the area that were attacked by storm surges the most times.This will inevitably cause plenty of losses to the coastl of bohai sea.Only typhoon Mamie in August 1985,caused the diret losses of 3.35 billion yuan to the coast of bohai sea.So it is of great significance to study the changes of tide level in the bohai sea,and to calculate the tidal level changes along the bohai sea during the typhoon.In this paper,after understanding the previous work about the storm surge,a new typhoon pressure field model and wind field model were putted forward,and it is proposed to provide wind field environment for storm surge's calculation.The pressure field model is proposed,after finding the generality of the dimensionless formula of Fujita model,Takahashi model and V.Bjerknes model,with the key parameter were repalaced by a new one.The wind field model is composed of two parts,the one is based on the gas particle's forces equilibrium assumption of the pressure gradient force,centrifugal force and coriolis force;the other part is to consider the shifting wind field proposed by typhoon movement on the wind field.Then the applicability is proved by the comparison of the dimensionless formula of the model,and the accuracy is proved by the simulation results of the actual typhoon.Then take the Reynold Navier-Stokes equations as the control equations of storm surge,divide the horizontal of computational domain evenly,divide the vertical of computational domain nonhomogeneous,and integrate it by layers,then through G.Fischer's theory which is “ half explicit-half implicit difference scheme” discrete equations and to solve.Given initial conditions and fixed boundary conditions,wind field environment is provided by the above pressure field and wind field model.However,the final calculation results are not ideal and still need to be improved.Finally,based on Hydroinfo software,the typhoon 6005 Polly,7203 Rita,8509 Mamie,9711 Winnie and 0509 Matsa were simulated in the bohai sea,and then the simulation of the tidal level,the simulation of the effects of the astronomical tide plus the storm surge were compared and verifield with the actual value.The verification results show that astronomical tide simulation results tally with the actual value of astronomical tide,the simulation results of the joint action of astronomical tide and storm surge can well reflect the variation of water level process,can be well calculate the maximum tidal level,so it can be proved that it has the practical feasibility and accuracy.