Three Dimensional Numerical Simulation Of The Interaction Between Ship Motion And Bridge Pier

With the development of land and water transportation,the number of bridges is increasing,and layout is more and more intensive.But the existence of the piers will hinder the smooth drainage of water flow in the channel,form a turbulent flow field around,which will make navigable flow conditions worsen.The development of shipping,ship for the increasingly large,further intensification of the contradiction between ship and bridge pier,collision between also occur,resulting in significant economic losses.Few set out to study the problem of navigating bridge area from the perspective of the coupling effect of ship motion and piers turbulence.In this paper,using the commercial software FLUENT to build the bridge between three-dimensional mathematical model,to study the ship by ship and pier pier turbulent coupling process;numerical simulation of each time step in the force and moment calculated by UDF,and calculated the next time step in the center of gravity position,line speed and the angular velocity,so as to realize the simulation of the coupling effect of ship motion and pier turbulence calculation model;the model consists of two computational domain by using multi region(regional dynamic and static area)so as to reduce the number of grids,and improve the dynamic mesh update speed and the mathematical model calculation speed;mainly analyzes the influence of ship bridge intersection in the process of the flow structure around the pier,the ship along the yaw force,the change trend of yaw moment and displacement of center of gravity,and a detailed analysis of the speed,velocity and distance on the ship bridge the ship impact force and gravity displacement,we draw the following conclusions:(1)Ship along the way by swaying force of pier and pier wake effect,showing repeated oscillation phenomenon,and have obvious peak,followed by a positive peak,negative peak and the positive peak;swaying force of the second positive peak was higher than that of the first high peak,and negative peak being larger than either;sway was positively correlated with peak force size and flow rate and the speed of the ship,and bridge spacing was inversely related;yawing moment magnitude and direction by transverse swing force magnitude and direction of the decision,the rules and the similar.(2)the speed and velocity of the yaw moment has great influence on the ship,but Spacing is less affected;spacing from 1.5D reduced to 0.6D,yawing moment of positive and negative peak only increased by about 50%,and the speed of the ship from 2.5m/s increases to 5.5m/s,bow and shake peak of negative torque increase by about 140%,flow rate from 1.5m/s increases to 3.0m/s bow rolling moment negative peak increased about 250%.(3)When the bridge distance at the same time,the ship bridge pier gravity displacement changes;when the bridge distance is 0.6D and 0.9D,the ship will bow outwards(away from the pier side),Fuo Asari(near the pier side)of the attitude across the pier,it will slightly increase the channel width required for ship’s navigation,and its center of gravity will be to move away from the pier,and when the ship to the pier,0.6D close distance;when the bridge distance is 1.2D and 1.5D,the basic line for barycenter trajectory of the ship bridge pier,with 4.2 ships along the sway force and yaw moment analysis,the speed is not greater than 2.5m/s,the premise of velocity no more than 2.0m/s,the bridge spacing is 1.2D or above,the pier on the sailing effect is very small.(4)When ship sailing speed is different,the ship’s center of gravity displacement changes during the ship sailed across the bridge pier.When ship speed is 2.5m/s or 3.5m/s,the ship is affected by the pier,ships passing with the posture: bow outward,the stern to the inside.Its center of gravity will first pier closer,then away,when the speed is 3.5m/s,the distance of the ship move close to the pier is long.When the ship speed is increased to 4.5m/s and 5.5m/s,ships passing with the posture: bow outward,the stern to the inside,then will gradually adjust hull to bow inward,outward gesture of passing the stern pier,its center of gravity continued to move close to the pier.(5)When the flow rate is different,the ship’s center of gravity displacement changes during the ship sailed across the bridge pier.Flow rate at 1.5m/s and 2.0m/s,the trend is the same.Ships will first focus slightly near the pier,then away.Flow rate at 2.5m/s and 3.5m/s,the trend is the same.The ships center of gravity will be a little far away from the pier firstly and then to close.