The article studies the oscillation features of the water in the square moon pool under the circumstances of wave-flow combined conditions. Comparing with the results of experiments of the square moon pool, a series o...The article studies the oscillation features of the water in the square moon pool under the circumstances of wave-flow combined conditions. Comparing with the results of experiments of the square moon pool, a series of studies reveal that the water piston oscillation phenomenon is quite similar to that of the circular one. Two types of oscillation are exhibited under different incoming wave periods, i.e. self-excited oscillation and forced oscillation. The difference between the circular and square moon pool is that the attack angle makes greater influences on the square one. "Beating phenomenon" is also found in the square moon pool which is not mentioned of the circular one.展开更多
An analytical solution is presented for the radiation and the diffraction of a cylindrical body with a moon pool floating on the surface of water with a finite depth. The expressions for the potentials are obtained by...An analytical solution is presented for the radiation and the diffraction of a cylindrical body with a moon pool floating on the surface of water with a finite depth. The expressions for the potentials are obtained by the method of separation of variables, and the unknown coefficients are determined by the boundary conditions and the matching requirements on the interface. The effects of the moon pool on the hydrodynamic characteristics of the body are investigated. Some peaks are observed on the curves of the added mass and damping coefficients, corresponding to the resonant frequencies of the moon pool. The internal free surface moves like a piston at a certain low resonant frequency.展开更多
The three-dimensional natural vibration characteristics of water inside a moon pool of an ocean structures are studied. The governing equations are derived based on the linear potential flow theory, and the boundary c...The three-dimensional natural vibration characteristics of water inside a moon pool of an ocean structures are studied. The governing equations are derived based on the linear potential flow theory, and the boundary condition of the total opening bottom suggested by Molin is adopted. A semi-analytical method is used to solve the governing equations, and the natural frequencies and the motion modes are obtained. Two types of motions are studied： （1） the piston motion in the vertical direction, and （2） the sloshing motion of the free surface. The influences of moon pool＇s structural parameters on the natural frequencies, and the modal shapes are analyzed.展开更多
In order to consider the viscous effect,the introduction of a parametric dissipation and new results are realized by applying the new formulation combining and dynamic conditions over the free-surface with viscous ter...In order to consider the viscous effect,the introduction of a parametric dissipation and new results are realized by applying the new formulation combining and dynamic conditions over the free-surface with viscous terms. The dispersion equation is then modified by assuming an additional term in the boundary condition at the free-surface and wave-number becomes complex number with a small imaginary part which ensures the decay of wave amplitudes. The comparisons of numerical results and model test measurement on wave elevation at the moon-pool center is obtained both for the peak period and for the amplitude at resonance by choosing an appropriated dissipation coefficient. The results show that the introduce dissipation is not only effective but also reliable to provide realistic predictions.展开更多
基金support of "111" project which was from China Education Department( No. B07019)
文摘The article studies the oscillation features of the water in the square moon pool under the circumstances of wave-flow combined conditions. Comparing with the results of experiments of the square moon pool, a series of studies reveal that the water piston oscillation phenomenon is quite similar to that of the circular one. Two types of oscillation are exhibited under different incoming wave periods, i.e. self-excited oscillation and forced oscillation. The difference between the circular and square moon pool is that the attack angle makes greater influences on the square one. "Beating phenomenon" is also found in the square moon pool which is not mentioned of the circular one.
基金supported by the Lloyd's Register Educational Trust (LRET) through the joint centre involving University College London,Shanghai Jiao Tong University and Harbin Engineering University,to which the authors are most grateful
文摘An analytical solution is presented for the radiation and the diffraction of a cylindrical body with a moon pool floating on the surface of water with a finite depth. The expressions for the potentials are obtained by the method of separation of variables, and the unknown coefficients are determined by the boundary conditions and the matching requirements on the interface. The effects of the moon pool on the hydrodynamic characteristics of the body are investigated. Some peaks are observed on the curves of the added mass and damping coefficients, corresponding to the resonant frequencies of the moon pool. The internal free surface moves like a piston at a certain low resonant frequency.
基金Project supported by the Natural Science Foundation of China(Grant No.51179125)the Greative Research Groups of the Natural Science Foundation of China(Grant No.51621092)the Natural Science Foundation of Tianjin(Grant No.16JCYBJC21200)
文摘The three-dimensional natural vibration characteristics of water inside a moon pool of an ocean structures are studied. The governing equations are derived based on the linear potential flow theory, and the boundary condition of the total opening bottom suggested by Molin is adopted. A semi-analytical method is used to solve the governing equations, and the natural frequencies and the motion modes are obtained. Two types of motions are studied： （1） the piston motion in the vertical direction, and （2） the sloshing motion of the free surface. The influences of moon pool＇s structural parameters on the natural frequencies, and the modal shapes are analyzed.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51079032)
文摘In order to consider the viscous effect,the introduction of a parametric dissipation and new results are realized by applying the new formulation combining and dynamic conditions over the free-surface with viscous terms. The dispersion equation is then modified by assuming an additional term in the boundary condition at the free-surface and wave-number becomes complex number with a small imaginary part which ensures the decay of wave amplitudes. The comparisons of numerical results and model test measurement on wave elevation at the moon-pool center is obtained both for the peak period and for the amplitude at resonance by choosing an appropriated dissipation coefficient. The results show that the introduce dissipation is not only effective but also reliable to provide realistic predictions.
