RANS-VOF Solver for Solitary Wave Run-up on A Circular Cylinder

Simulation of solitary wave run-up on a vertical circular cylinder is carried out in a viscous numerical wave tank developed based on the open source codes Open FOAM. An incompressible two-phase flow solver naoe-FOAM-SJTU is used to solve the Reynolds-Averaged Navier–Stokes（RANS） equations with the SST k ？？ turbulence model. The PISO algorithm is utilized for the pressure-velocity coupling. The air-water interface is captured via Volume of Fluid（VOF） technique. The present numerical model is validated by simulating the solitary wave run-up and reflected against a vertical wall, and solitary wave run-up on a vertical circular cylinder. Comparisons between numerical results and available experimental data show satisfactory agreement. Furthermore, simulations are carried out to study the solitary wave run-up on the cylinder with different incident wave height H and different cylinder radius a. The relationships of the wave run-up height with the incident wave height H, cylinder radius a are analyzed. The evolutions of the scattering free surface and vortex shedding are also presented to give a better understanding of the process of nonlinear wave-cylinder interaction.

WAVE CURRENT FORCE COEFFICIENTS ON INCLINED CYLINDER AND A NEW ESTIMATION METHOD

Based on the review of present force coefficients estimation methods, a new method in the frequency domain, revised cross-spectrum estimation method, is presented in this paper. Some experiments on the wave-current force on inclined cylinders are also described and the wave current force coefficients are estimated by the revised cross-spectrum estimation method. From the results, it is found that the wave and current directions have some regular effect on the coefficients. According to the results, some empirical formulas are obtained for converting the wave-current force coefficients on inclined cylinders into a unified coefficient. Comparisons show that the unified coefficients are in good agreement with other results.

FORCES ON CYLINDERS IN COEXISTING FIELD OF REGULAR WAVES AND CURRENTS

Based on the linear wave theory, the lift force on the cylinder under the action of both regular waves and currents related to inline force and the resultant force has been investigated. The relationship between the hydrodynamic coefficients of resultant force Cf, of drag force Cd, of inertia force Cm and of lift force CL and the redefined KC number is reported. It is indicated that in a certain region of KC number, the influence of lift force on the resultant force can not be ignored.

Nonlinear effect on inertia component of wave forces on a cylinder

A series of experiments on wave forces on a cylinder have been carried out when inertia component isdominant for a small she cylinder. The influence of nonlinear effect on the inertia component of wave forces on a cylinder is analyzed. The applicable range of nonlinear wave theories, such as Stokes and cnoidal wave theories, in calculating wave forces on a cylinder is discussed. A correction method is suggested for linear wave theory in calculated waveforces on a cylinder under the nonlinear condition.

Theoretical investigation of laser-generated guided waves in hollow cylinders

The problem of the laser-generated guided elastic waves in hollow cylinders is inves-tigated numerically by using the method of eigen-function expansion. The explicit expression of the transient waveform is given for the case of the outer surface of the hollow cylinder beat axi-symmetrically by four laser pulses with same energy. The characteristics of the transient waveform are explained based on the dispersive relations.

A 3-D numerical study of solitary wave interaction with vertical cylinders using a parallelised particle-in-cell solver

This paper aims to provide a better understanding of the interaction between solitary waves and vertical circular cylinders. This is achieved via process based numerical modelling using the parallel particle-in-cell based incompressible flow solver PICIN. The numerical model solves the Navier-Stokes equations for free-surface flows and incorporates a Cartesian cut cell method for fluid-structure interaction. Solitary waves are generated using a piston-type wave paddle. The PICIN model is first validated using a test case that involves solitary wave scattering by a single vertical cylinder. Comparisons between the present results and experimental data show good agreement for the free surface elevations around the cylinder and the horizontal wave force on the cylinder. The model is then employed to investigate solitary wave interaction with a group of eleven vertical cylinders. The wave run-up and wave forces on the cylinders are discussed.

柱面内爆驱动下铅飞层对碰区动载行为的实验研究

采用光学阴影照相和脉冲X光照相,对柱面内爆对碰驱动下铅飞层对碰区凸起行为进行了实验研究。实验结果显示,铅飞层对碰区出现严重的射流状超前凸起,凸起行为表现出明显的失稳发展倾向。由于对碰产生高压,因此铅飞层对碰区可能完全熔化,变成名义上无剪切强度的流体。材料的低强度、低熔点(冲击熔化压力)性能是造成铅飞层对碰区出现射流状超前凸起现象的主要因素。还观察到对碰区出现3个超前凸起现象,初步分析可能是由于柱面滑移爆轰波对碰导致的波系反射、叠加造成的,具体原因还有待于进一步分析研究。