CFD evaluation and experimental comparison on the flow around fixed multi-column configurations
CFD evaluation and experimental comparison on the flow around fixed multi-column configurations
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DOI：
10.1007/s40868-019-00066-z
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发表时间：
2019-10
影响因子：
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通讯作者：
P. Lopes;G. Rosetti;N. H. Hannes;M. Chame;S. Hirabayashi;Hideyuki Suzuki;Rodolfo T. Gonçalves
中科院分区：
文献类型：
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作者：
P. Lopes;G. Rosetti;N. H. Hannes;M. Chame;S. Hirabayashi;Hideyuki Suzuki;Rodolfo T. Gonçalves
平台的流致运动(FIM)是一个亟待研究的重要现象，以帮助设计人员和降低与系泊和立管系统相关的成本。在这个问题上，当谈到多柱构型时，俘获试验(也称为固定或静止试验)可以是一种值得研究的方法，可以用来研究涡旋分离、振荡升力的来源、阻力以及上游柱的尾迹对下游柱的干扰。采用计算流体力学(CFD)方法对一、三、四个固定排列的低长宽比(柱吃水与柱面尺寸之比)的柱的绕流进行了计算流体力学评价。测试了三种不同形状的柱形截面，即圆形、方形和菱形。对于多柱结构，测试的间距比为(其中是从中心到每一柱的中心的距离)。测试的雷诺数为10万。针对流体力学积分量，对各柱内的升力和阻力进行了监测，并与实验结果进行了比较。还观察到了速度场和涡量场的时间平均值。计算使用流动求解器StarCCM+进行；该程序求解多相不可压缩非定常雷诺平均N-S方程(URANS)。采用改进的延迟分离涡模拟(IDDES)方法进行了数值模拟。IDDES用雷诺平均Navier-Stokes(RANS)模型估算物体边界附近的小湍流尺度，用大涡模拟(LES)模型估算大尺度湍流。对于流体体积(VOF)，采用了界面捕捉法。与单柱相比，多柱阵列没有呈现出规则的旋涡脱落模式。旋涡脱落行为主要由柱体截面决定。对于多柱配置，柱的数量，3或4，不是主要问题。CFD计算结果与实验结果对比表明，圆形和方形情况吻合较好，而钻石情况差异较大，有待进一步研究。
The flow-induced motion (FIM) of platforms is a vital phenomenon issue to be investigated to help the designers and to decrease the costs related to the mooring and/or riser systems. On this matter, when talking about multi-column configurations, captive tests (also called fixed or stationary tests) can be a methodology worth of examining the vortex detachments, the source for the oscillatory lift, the drag force, and the interference of the wake of the upstream column on the downstream ones. Computational fluid dynamics (CFD) evaluations on the flow around a fixed array of one, three, and four columns with low aspect ratio,(the ratio between the column draft,, and the column face dimension,) were conducted. Three different shapes of the column sections were tested, namely, circular, square, and diamond. For the multi-column configurations, the spacing ratio tested was(whereis the distance from center to center of each column). The Reynolds number tested was 100,000. Lift and drag forces were monitored in each column aiming at the integral quantities of the hydrodynamic to compare with the experimental results. Time averages of velocities and vorticity fields were also observed. The calculations were performed with the flow solver StarCCM+; the code solves the multi-phase incompressible Unsteady Reynolds-Averaged Navier–Stokes (URANS) equations. Simulations were carried out with the Improved Delayed Detached Eddy Simulation (IDDES) method. The IDDES estimates the small turbulence scales near the body boundary with the Reynolds-Averaged Navier–Stokes (RANS) model and the large scales with the Large Eddy Simulation (LES) model. For the volume of fluid (VoF), an interface-capturing approach was used. The multi-column arrays presented no regular vortex shedding pattern when compared with the single-column case. The vortex shedding behavior was mainly determined by the column section. For the multi-column configurations, the number of columns, 3 or 4, was not the main issue. CFD calculations compared with the experiments showed good agreement for the circular and square cases and a significant difference for the diamond cases, which need to be further investigated.