通过对恒定雷诺数Re=80、理查森数Ri范围为-5≤Ri≤-0.5的冷圆柱绕流开展三维数值模拟，研究冷圆柱绕流尾迹结构的形成机理及浮力对尾迹结构的影响。结果表明，在-2.5≤Ri≤-0.5范围内，冷圆柱绕流的尾迹结构受到浮力作用呈现出一致的循环模式，当Ri达到一定值（如Ri=-5）时，冷圆柱绕流的循环模式发生改变。随着Ri减小冷圆柱尾迹结构整体向重力方向偏转，肋部结构数量呈现非单调变化，柱体尾迹的贴壁流动增强，当Ri减小到一定值时流动尾迹仅从圆柱下方发生分离。圆柱表面的升力系数、阻力系数和努塞尔数随Ri的减小而单调增加。

This article utilizes three-dimensional numerical simulations on the flow around a cold cylinder with a constant Reynolds number （Re=80） and a Richardson number （Ri） ranging from -5 to -0.5， to investigate the formation mechanism of the wake structure and the influence of buoyancy on the wake structure. The results indicate that within the range of -2.5≤Ri≤-0.5， the wake structure around the cold cylinder exhibits a consistent cyclic pattern due to the influence of buoyancy. AsRireaches a certain threshold （e.g.， Ri=-5）， the cyclic pattern of the cold cylinder flow undergoes a change. With the decrease of Ri， the overall wake structure of the cold cylinder deflects in the direction of gravity， while the number of rib structures exhibits a non-monotonic variation， and the wall-attached flow of the cylinder wake intensifies. When Ri decreases to a certain threshold， flow separation occurs solely from beneath the cylinder. The lift and drag coefficients， along with the Nusselt number on the cylinder’s surface， increase monotonically as Ri decreases.