The development of a two dimensional numerical wave tank （NWT） with a rocker or piston type wavemaker based on the high order boundary element method （BEM） and mixed Eulerian-Lagrangian （MEL） is examined. The ca...The development of a two dimensional numerical wave tank （NWT） with a rocker or piston type wavemaker based on the high order boundary element method （BEM） and mixed Eulerian-Lagrangian （MEL） is examined. The cauchy principle value （CPV） integral is calculated by a special Gauss type quadrature and a change of variable. In addition the explicit truncated Taylor expansion formula is employed in the time-stepping process. A modified double nodes method is assumed to tackle the comer problem, as well as the damping zone technique is used to absorb the propagation of the free surface wave at the end of the tank. A variety of waves are generated by the NWT, for example; a monochromatic wave, solitary wave and irregular wave. The results confirm the NWT model is efficient and stable.展开更多
In this paper,the two-dimensional Rayleigh-Taylor(RT) instability is directly simulated using the moving particle semiimplicit(MPS) method,which is based on the fully Lagrangian description.The objectives of this pape...In this paper,the two-dimensional Rayleigh-Taylor(RT) instability is directly simulated using the moving particle semiimplicit(MPS) method,which is based on the fully Lagrangian description.The objectives of this paper are to investigate preliminarily the effect of viscosity and finite size domain on the evolution of the RT instability.The simulation results demonstrate that(1) the mushroom-like vortex motions are formed in late time due to fluid viscosity,which give rise to the secondary shear flow instability,(2) the finite thickness of the fluid layer limits the development of the RT instability.The above results are consistent with the experiments and theoretical analyses.Meanwhile,the linear growth rate of the RT instability obtained from the numerical simulation is also in agreement with theoretical analyses.And the nonlinear threshold from the simulation result is comparable with the theoretical estimate.Two stages of the nonlinear evolution of the RT instability are revealed in the numerical simulation,nonlinear saturation and turbulent mixing.展开更多
基金Foundation item： Supported by the National Natural Science Foundation of China （Grant No.51009038/E091002）.
文摘The development of a two dimensional numerical wave tank （NWT） with a rocker or piston type wavemaker based on the high order boundary element method （BEM） and mixed Eulerian-Lagrangian （MEL） is examined. The cauchy principle value （CPV） integral is calculated by a special Gauss type quadrature and a change of variable. In addition the explicit truncated Taylor expansion formula is employed in the time-stepping process. A modified double nodes method is assumed to tackle the comer problem, as well as the damping zone technique is used to absorb the propagation of the free surface wave at the end of the tank. A variety of waves are generated by the NWT, for example; a monochromatic wave, solitary wave and irregular wave. The results confirm the NWT model is efficient and stable.
基金supported by the National Natural Science Foundation of China (Grant No. 50476008)
文摘In this paper,the two-dimensional Rayleigh-Taylor(RT) instability is directly simulated using the moving particle semiimplicit(MPS) method,which is based on the fully Lagrangian description.The objectives of this paper are to investigate preliminarily the effect of viscosity and finite size domain on the evolution of the RT instability.The simulation results demonstrate that(1) the mushroom-like vortex motions are formed in late time due to fluid viscosity,which give rise to the secondary shear flow instability,(2) the finite thickness of the fluid layer limits the development of the RT instability.The above results are consistent with the experiments and theoretical analyses.Meanwhile,the linear growth rate of the RT instability obtained from the numerical simulation is also in agreement with theoretical analyses.And the nonlinear threshold from the simulation result is comparable with the theoretical estimate.Two stages of the nonlinear evolution of the RT instability are revealed in the numerical simulation,nonlinear saturation and turbulent mixing.
