A Study On Ship Maneuvering Around A Pier By Using Numerical Simulation

With the rapid development of the transport industry,a large number of bridges were constructed over the river and the sea,accompanied a considerable number of bridge piers.Bridge piers played a supporting role in the water but destroyed the original channel flow fields,and the changes of the flow fields would inevitably be against to the navigation of the ships that passed the bridge piers,which brought the problem of ship maneuvering and control around bridge piers.The possibility of ships colliding with obstacles including the coast,bridges,ships etc.was low.However,once occurred,the collision was likely to lead to a catastrophe.In this study,CFD numerical simulation method and ship model experiments were used to investigate the problem of ship navigation and maneuvering under different current speed around a pier,which made sense in ship-bridge collision avoidance and navigation safety assessment techniques.This article was accomplished at several aspects:(1)Research methods and current status of the ship-bridge problems were reviewed and summarized.The basic theory of computational fluid dynamics was encapsulated and the unsteady,viscous,incompressible fluid equations were established including RNGk-? turbulence model and VOF two-phase model.(2)By means of CFD numerical simulation using VOF two-phase method and scaled model experiments under different current speed and different flow angles,the speeds of feature points around a pier were measured to investigate the distribution of the flow field around a pier.The comparison of the results in both methods validated the effectiveness of the numerical simulation methods.The influencing area 3.3B(B is the width of the pier)from the side of the pier was achieved.(3)By means of CFD numerical simulation using two-dimension dynamic meshing method,the maneuvering motion of the ship passing the bridge pier under different current speeds and different distance from the side of the pier was studied.The influence area 2(L+l)(L,l was the length of the ship,pier,respectively)along the longitudinal axis of the pier was achieved and the conclusion of 3.3B was verified.(4)Based on the results of CFD numerical simulation and scaled model experiments,the range of the current speed and influence area were presented.Current speed was the main factor that influenced the ship maneuvering motion around a pier.At low flow speed,the ship could pass the bridge through a reasonable steering but was not easy to keep heading at a high speed(0.5 times the speed of the ship)even through the steering.It can be seen from the numerical simulation analysis that under different current speeds,the bridge pier would lower the current speed of the water before and behind the pier,and heighten it on both sides of the pier.Under different current speeds,a 2(L+l)x7.6B area was designated as the ship navigation influence area,and in the influence area,ships would not be easy to maneuver and outside of the influence area was safety area that had a limited impact on ship maneuvering motion.