A numerical model has been developed to study sloshing of turbulent flow in a tank with elastic baffles. The Moving-Particle Semi-implicit method(MPS) is a kind of meshless Lagrangian calculation method. The large edd...A numerical model has been developed to study sloshing of turbulent flow in a tank with elastic baffles. The Moving-Particle Semi-implicit method(MPS) is a kind of meshless Lagrangian calculation method. The large eddy simulation(LES) approach is employed to model the turbulence by using the Smagorinsky Sub-Particle Scale(SPS)closure model. This paper uses MPS-FSI method with LES to simulate the interaction between free surface flow and a thin elastic baffle in sloshing. Then, the numerical model is validated, and the numerical solution has good agreement with experimental data for sloshing in a tank with elastic baffles. Furthermore, under external excitations,the MPS is applied to viscous laminar flow and turbulent flow, with both the deformation of elastic baffles and the wave height of the free surface are compared with each other. Besides, the impact pressure with/without baffles and wave height of free surface are investigated and discussed in detail. Finally, preliminary simulations are carried out in the damage problem of elastic baffles, taking the advantage of the MPS-FSI method in computations of the fluid–structure interaction with large deformation.展开更多
Offshore structures are subject to environmental loads such as waves,currents,or wind,which may induce cyclic lateral vibration at the foundations.These cyclic vibration loadings may affect the rheological property of...Offshore structures are subject to environmental loads such as waves,currents,or wind,which may induce cyclic lateral vibration at the foundations.These cyclic vibration loadings may affect the rheological property of the sediments adjacent to the foundation and the stability of the structures.This is especially true when the structures are founded on cohesive sedimentary bed.In this study,the viscosity of soft cohesive sediments adjacent to a vibrating pillar was considered,and as a primary index of the rheological characteristics of the sediments.The investigation was performed using the sinking ball method.The experimental findings indicated that the viscosity of cohesive sediments decrease with increase of the liquidity index and vibration intensity.A simple semi-empirical formula was proposed.The structures of the cohesive sediments were destroyed due to the mechanical vibration,and the sediments were fluidized during vibration loads.The shear strength of the cohesive sediments decreased with increased vibration intensity,not only because of the increased pore water pressure but also the decreased viscosity of cohesive sediments following sediment fluidization.展开更多
The submarine Hydrodynamic coefficients are predicted by numerical simulations. Steady and unsteady Reynolds Averaged Navier-Stokes （RANS） simulations are carried out to numerically simulate the oblique towing exper...The submarine Hydrodynamic coefficients are predicted by numerical simulations. Steady and unsteady Reynolds Averaged Navier-Stokes （RANS） simulations are carried out to numerically simulate the oblique towing experiment and the Planar Motion Mechanism （PMM） experiment performed on the SUBOFF submarine model. The dynamic mesh method is adopted to simulate the maneuvering motions of pure heaving, pure swaying, pure pitching and pure yawing. The hydrodynamic forces and moments acting on the maneuvering submarine are obtained. Consequently, by analyzing these results, the hydrodynamic coefficients of the submarine maneuvering motions can be determined. The computational results are verified by comparison with experimental data, which show that this method can be used to estimate the hydrodynamic derivatives of a fully appended submarine.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51479116 and 11272213)
文摘A numerical model has been developed to study sloshing of turbulent flow in a tank with elastic baffles. The Moving-Particle Semi-implicit method(MPS) is a kind of meshless Lagrangian calculation method. The large eddy simulation(LES) approach is employed to model the turbulence by using the Smagorinsky Sub-Particle Scale(SPS)closure model. This paper uses MPS-FSI method with LES to simulate the interaction between free surface flow and a thin elastic baffle in sloshing. Then, the numerical model is validated, and the numerical solution has good agreement with experimental data for sloshing in a tank with elastic baffles. Furthermore, under external excitations,the MPS is applied to viscous laminar flow and turbulent flow, with both the deformation of elastic baffles and the wave height of the free surface are compared with each other. Besides, the impact pressure with/without baffles and wave height of free surface are investigated and discussed in detail. Finally, preliminary simulations are carried out in the damage problem of elastic baffles, taking the advantage of the MPS-FSI method in computations of the fluid–structure interaction with large deformation.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.52001206).
文摘Offshore structures are subject to environmental loads such as waves,currents,or wind,which may induce cyclic lateral vibration at the foundations.These cyclic vibration loadings may affect the rheological property of the sediments adjacent to the foundation and the stability of the structures.This is especially true when the structures are founded on cohesive sedimentary bed.In this study,the viscosity of soft cohesive sediments adjacent to a vibrating pillar was considered,and as a primary index of the rheological characteristics of the sediments.The investigation was performed using the sinking ball method.The experimental findings indicated that the viscosity of cohesive sediments decrease with increase of the liquidity index and vibration intensity.A simple semi-empirical formula was proposed.The structures of the cohesive sediments were destroyed due to the mechanical vibration,and the sediments were fluidized during vibration loads.The shear strength of the cohesive sediments decreased with increased vibration intensity,not only because of the increased pore water pressure but also the decreased viscosity of cohesive sediments following sediment fluidization.
基金Project supported by the National Natural Science Foundation of China(Grant No.11272213)
文摘The submarine Hydrodynamic coefficients are predicted by numerical simulations. Steady and unsteady Reynolds Averaged Navier-Stokes （RANS） simulations are carried out to numerically simulate the oblique towing experiment and the Planar Motion Mechanism （PMM） experiment performed on the SUBOFF submarine model. The dynamic mesh method is adopted to simulate the maneuvering motions of pure heaving, pure swaying, pure pitching and pure yawing. The hydrodynamic forces and moments acting on the maneuvering submarine are obtained. Consequently, by analyzing these results, the hydrodynamic coefficients of the submarine maneuvering motions can be determined. The computational results are verified by comparison with experimental data, which show that this method can be used to estimate the hydrodynamic derivatives of a fully appended submarine.
