Abstract: From the pansystems view of prediction, the paper investigates the blow-up andpost blow-up of fluid in rotation and convergence.The results show that the motion includes certain characteristics of reverse transformation the counter clockwiserotation can be developed into clockwise,and vice versa;the convergence can be changed into divergence through blow-up, and the divergence will die out continuously.The real forecasting must look this mechanism in the face. Generally speakinq, theforecasting of evolution for fluid can’t be considered only as traditional Cauchy pro-blem. The traditional forecast models should be rediscussed questioningly.

Key words: transition position, incompressible boundary layer, parabolized stability equation (PSE), numerical simulation