Research On The Influence Of Flow On The Sinking Of Bulk Carriers Based On CFD Simulation

As an important calculation method for loading and unloading cargo of bulk carriers,dipstick weighing has the advantages of simple procedures,time saving and high efficiency,but with the development of larger ships,the accuracy requirements for dipstick weighing are also higher.However,due to the difference of flow velocity near the waters of some ports,terminals and anchorages where the dipstick is measured,it leads to the sinking of ship hull,which affects the accuracy of dipstick weight counting.Therefore,it is necessary to study the effect of the flow of these waters on the sinking amount of bulk carriers.Nowadays,with the rapid progress of computer technology and the development and wide application of CFD technology,we can make more accurate and fast forecast on the effect of flow on the sinking of bulk carriers through CFD technology,so as to reduce the error caused by flow in the process of dipstick weighing,improve the accuracy of weighing and reduce the trade disputes.In this paper,we take a Panamax bulk carrier as an example to test and analyze the effect of sinking volume of bulk carrier due to flow by CFD method,and the specific research process and content are as follows.Firstly,Solidworks software is selected to establish a three-dimensional geometric ship model based on the ship profile information,and then the established model is imported into STAR-CCM+ for the test.The calculation domain is determined,the mesh is divided,the calculation model is set,and then the numerical simulation of the ship sinking under different water depth draft ratio and different flow speed conditions is carried out according to the calculation process.After the results are obtained from the numerical simulation,the results are compared with the results of the physical model pool test at Dalian University of Technology to check the accuracy and reliability of the CFD numerical simulation.Finally,SPSS software was used to regress the numerical simulation results to determine the linear regression equation of flow velocity on the sinking volume of bulk carriers under different water depth-draft ratio conditions,and the reliability of the linear regression equation was evaluated by this software.The results of the numerical simulation of sinking CFD were compared with the pool test results,and the results showed a good agreement between the two test results.After comparing the two test validations,it is proved that the numerical simulation test of STAR-CCM+ can be used as a tool for the rapid prediction of the sinking amount of the flow-to-bulk carrier hull.The numerical simulation and analysis of various water depth/draught ratios and current speed conditions by CFD software show that the sinking volume of bulk carrier hull under three water depth/draught conditions in shallow water,and the sinking volume of the ship under each speed is larger than that under deep water conditions,and the sinking volume keeps increasing as the water depth/draught ratio decreases.Under each water depth/draught condition,the sinking volume of the ship as a whole increases with the increase of the flow velocity in the water near the hull.The linear regression equation with good fit and significance was obtained by regression analysis,which showed that the sinking volume had a significant linear relationship with the current speed and water depth/draught ratio,and the effect of current speed on the sinking volume was greater than the effect of water depth/draught ratio on the sinking volume.