It is discovered that the shape of the secondary flow is changed from one vortex to two vortexes with the increment of Dean number. But the appear of the second vortex of power-law fluid is later than that of Newtonian fluid.

• 研究发现，随着Dean数的增大，二次流的形状由一个涡场变为两个涡场，幂律流体比牛顿流体滞后出现第二个涡场。