A method is presented to calculate the resistance of a high-speed displacement ship taking the effect of sinkage and trim and viscosity of fluid into account.A free surface flow field is evaluated by solving Reynolds ...A method is presented to calculate the resistance of a high-speed displacement ship taking the effect of sinkage and trim and viscosity of fluid into account.A free surface flow field is evaluated by solving Reynolds averaged Navier-Stokes(RANS) equations with volume of fluid(VoF) method.The sinkage and trim are computed by equating the vertical force and pitching moment to the hydrostatic restoring force and moment.The software Fluent,Maxsurf and MATLAB are used to implement this method.With dynamic mesh being used,the position of a ship is updated by the motion of "ship plus boundary layer" grid zone.The hull factors are introduced for fast calculating the running attitude of a ship.The method has been applied to the ship model INSEAN2340 for different Froude numbers and is found to be efficient for evaluating the flow field,resistance,sinkage and trim.展开更多
We consider two major components of the drag of a ship, the ＂friction drag＂ and the ＂wave drag＂, that are related to viscous friction at the hull surface and wavemaking, and mostly depend on the Reynolds number an...We consider two major components of the drag of a ship, the ＂friction drag＂ and the ＂wave drag＂, that are related to viscous friction at the hull surface and wavemaking, and mostly depend on the Reynolds number and the Froude number, respectively. We also consider the influence of sinkage and trim, viscosity, and nonlinearities on the drag. The sum of the friction drag given by the classical ITTC friction formula and the wave drag predicted by the modification, called Neumann-Michell （NM） theory, of the classical Neumann-Kelvin theory of ship waves is found to be within about 10% of experimental drag measurements for four ship hulls for which theoretical predictions and experimental measurements are compared. The sum of the ITTC friction drag and the NM wave drag can then be expected to yield realistic practical estimates that can be useful for routine applications to design and hull- form optimization of a broad range of displacement ships. Furthermore, we note several simple extensions of this highly simplified approach that can be expected to significantly improve accuracy.展开更多
基金the National Natural Science Foundation of China (No.50879090)the Advanced Research Program of GAD of the P.L.A (No.7131005)
文摘A method is presented to calculate the resistance of a high-speed displacement ship taking the effect of sinkage and trim and viscosity of fluid into account.A free surface flow field is evaluated by solving Reynolds averaged Navier-Stokes(RANS) equations with volume of fluid(VoF) method.The sinkage and trim are computed by equating the vertical force and pitching moment to the hydrostatic restoring force and moment.The software Fluent,Maxsurf and MATLAB are used to implement this method.With dynamic mesh being used,the position of a ship is updated by the motion of "ship plus boundary layer" grid zone.The hull factors are introduced for fast calculating the running attitude of a ship.The method has been applied to the ship model INSEAN2340 for different Froude numbers and is found to be efficient for evaluating the flow field,resistance,sinkage and trim.
基金partly supported by the Office of Naval Research
文摘We consider two major components of the drag of a ship, the ＂friction drag＂ and the ＂wave drag＂, that are related to viscous friction at the hull surface and wavemaking, and mostly depend on the Reynolds number and the Froude number, respectively. We also consider the influence of sinkage and trim, viscosity, and nonlinearities on the drag. The sum of the friction drag given by the classical ITTC friction formula and the wave drag predicted by the modification, called Neumann-Michell （NM） theory, of the classical Neumann-Kelvin theory of ship waves is found to be within about 10% of experimental drag measurements for four ship hulls for which theoretical predictions and experimental measurements are compared. The sum of the ITTC friction drag and the NM wave drag can then be expected to yield realistic practical estimates that can be useful for routine applications to design and hull- form optimization of a broad range of displacement ships. Furthermore, we note several simple extensions of this highly simplified approach that can be expected to significantly improve accuracy.
