Numerical Simulation Of Deformation Characteristics Of Hanging Silt Curtains Under Currents

With the increasing environmental protection of water,silt curtains are being used more and more widely in the channel dredging,river and lake treatment and other areas.Silt curtains can be generally divided into two types:hanging silt curtains and standing silt curtains.Hanging silt curtains are the preferred type.Because silt curtains is easy to deploy and maintain.But,hanging silt curtains often have large deformations under current,which greatly affect the application effect and engineering cost.Therefore,it is of great practical engineering significance to explore the deformation characteristics of the hanging silt curtain.In order to explore the deformation problem of silt curtain under the interaction of water flow and structure,a two-dimensional numerical model of silt curtain was established.Using a two way fluid-structure interactions method,and use dynamic mesh control technology,the large displacement and large deformation of the silt curtain are realized.The vertical deformation of the silt curtain after reaching the balance under current was studied.By changing the water flow velocity U,the silt curtain length L and the counterweight M,the influence of the above factors on the flow field characteristics around the silt curtain,the deformation characteristics of the silt curtain and the force characteristics are analyzed.The results reveal that,(1)The flow field behind the silt curtain can be divided into a near-bed jet flow and a recirculation region.The size of the recirculation zone after the curtain increases with the growth of the curtain length and the flow velocity,and the maximum velocity of the near-bed jet flow also shows a similar change law.In general,the change of the counterweight has little effect on the flow field.But as the counterweight increases,the size of the partition flow field after the curtains will increase.(2)The drag coefficient Cd decreases as the flow velocity U increases,and increases with the increase of the curtain length L and the weight M;The lift coefficient C1 increases with the increase of the flow velocity U and the curtain length L,and decreases as the weight M increases.(3)The effects of different parameters on the horizontal displacement of the bottom end of the silt curtain Dx,the effective depth H,the curtain inclination θ and the bending coefficient K of the silt curtain were analyzed.The horizontal displacement Dx,the inclination θ and the bending coefficient K of the silt curtain increase with the increase of the flow velocity U and the curtain length L,and decrease with the increase of the weight;The effective depth H decreases as the flow velocity U increases,and increases as the curtain length L and the weight M increase.The influence of the weight of the same curtain length on the relative horizontal displacement Dx,the effective depth H,the inclination θ,and the bending coefficient K increases with the increase of the flow velocity.The effect of the weight on the effective depth H and the bending coefficient K at the same flow velocity increases as the curtain length L increases.(4)The two key design parameters of the horizontal displacement Dx and the effective depth H of the silt curtain are dimensionless with the influence factors such as the velocity U,the curtain length L and the weight M,respectively.Multivariate nonlinear regression analysis was performed.Two prediction formulas for the horizontal displacement of the bottom end of the silt curtain Dx and the effective depth H are obtained.The calculated value is compared with the predicted value,and the correlation between the two is good.