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应用基于浸入边界法的三维水动力并行计算程序CgLES_IBM,并结合隐式结构动力计算程序X-code,对倾斜角度为60°来流作用下的细长柔性立管涡激振动进行了直接数值模拟。研究发现:柔性立管振动位移表现出明显的驻波特征,振动频谱呈现单谱模式,绝大部分的振动能量集中在一个窄频段上,能量的分布与振型一致。立管两向振动的相位差沿展向周期变化,在顺流向振动结点处出现180°的相位切换。与此对应,立管的振动轨迹也出现了逆时针和顺时针“8”字形的变化。流体力的时空分布呈现行波和驻波的混合模式。涡激振动在立管的大部分范围内处于激励状态,仅在横流向振动结点以下一定范围内处于阻尼状态。尾流模式表现为倾斜泻涡模式,导致了流体力呈现出一定的行波特征。
A three-dimensional hydrodynamic parallel calculation program Cgles_IBM based on the immersion boundary method and X-code of implicit structural dynamics were applied to directly simulate the vortex-induced vibration of slender flexible risers with a 60 ° angle of inclination . The results show that the vibrational displacement of flexible riser shows obvious standing wave characteristics. The vibrational spectrum shows single spectrum mode, most of the vibration energy is concentrated in a narrow frequency band, and the energy distribution is consistent with the mode shape. The phase difference of the riser two-way vibration changes along the span direction, and a phase shift of 180 ° occurs along the downstream vibration node. Corresponding to this, there is a change in the anti-clockwise and clockwise “8” -shape of the riser’s vibrational trajectory. The spatio-temporal distribution of fluid forces presents a mixed mode of traveling and standing waves. Vortex-induced vibration in most of the standpipe in the excitation state, only in the cross-flow below the vibration node within a certain range of damping. The wake mode shows a ramp-eddy mode, which leads to the fluid force showing some traveling wave characteristics.