双圆柱的入水参数对水作用力的影响

为了分析多圆柱入水的各个状态参数对圆柱所受水作用力的影响,本文采用了CFD方法对双圆柱同步常速入水这一物理过程进行了动态数值模拟。采用变密度的不可压缩Euler方程作为控制方程,通过求解密度域的接触间断来追踪自由液面。基于直角切割网格系统,采用Roe型的Upwind格式的有限体积法作数值离散。采用双时间推进法和人工压缩法来进行时域步进。相对单圆柱入水的受力而言,本文对双圆柱相互作用所引起的附加水作用力,采用数值拟合的方法,提出了简单的代数表达式。然后分别以双圆柱的半径、间距和入水速度作为状态参数,定量地分析了这些参数对附加水作用力的影响,综合构造出可用于任意双圆柱同步入水模型的附加水作用力的估算表达式。本文的思想方法也可用在多柱状体的工程结构的入水分析中。

Influence of parameters of twin cylinders on hydrodynamic during synchronous water entry

To study the influence of various parameters of multiple cylinders on the hydrodynamic forces acting on the cylinder. The article presents CFD method to numerically simulate the physical process of twin cylinders synchronous entering water vertically at constant speed. The incompressible Euler equations for a variable density fluid are taken as the governing equation, in which free surface is treated as a contact discontinuity. Based on Cartesian cut cell mesh system, the finite volume method with Roe's approximate Riemann solver and upwind scheme are used for numerical discretization, and the implicit dual time-stepping technique and artificial compressible method are adopted on time advancing. For the additional force due to the interaction of twin cylinders, simple algebraic expressions are proposed by using numerical fitting method. Furthermore, the effect of status parameters (such as radius, distance and velocity of twin cylinders) on the additional force is quantitatively analyzed. Finally, an empirical representation involving all status parameters is constructed and hopefully can be used in the water entry of multiple columnar engineering structures.