深海立管系统排布密集，立管之间的相互干涉问题广泛存在。基于自主开发的深海立管涡激振动求解器vivFOAMSJTU，以标准问题为基础，研究了阶梯来流下，不同串列立管间距对上游和下游立管涡激振动的影响。数值模拟的立管间距从立管直径的1倍变化至4倍。计算结果表明： 上游立管几乎不受立管间距的影响，其振动模态与孤立管相同，同为4阶；下游立管由于串列立管间的干涉作用，其振动模态比上游立管低，不同间距下均表现为3阶。下游立管受立管间距的影响明显，随着间距的增加，3阶模态的权重逐渐减小而4阶模态的权重逐渐增加。

 Risers are grouped in close proximity in engineering. The interference of two tandem arranged risers widely exists. The selfdeveloped solver viv-FOAM-SJTU is adopted for the prediction of the time-domain voxtex-induced vibration （VIV） response of deep-ocean risers. After the study of the benchmark case， the simulations of VIV of two tandem arranged risers with different spacings are carried out. The distance between two risers is changed from D to 4Dwhere D is the riser diameters. The results show that the distance between risers has little effect on the vibration mode. The VIV responses of the upstream riser with different spacing are fall dominated by the 4th mode， which is the same with the isolated riser. The VIV mode of the downstream riser is lower than the upstream one because of the interference between two risers. The responses of the downstream riser with different spacings are dominated by the 3rd mode. While， the distance between risers has a great impact on the trailing riser. With the increase of the distance， for the trailing riser， the weight of the 3rd mode decreases， and the weight of the 4th mode increases.