Direct numerical simulation for flow field with three dimensional turbulent mixed layers has been carried out by using pseudospectrum

the evolution process of flow direction vortex and of expand direction vortex for the flow field

as well as three dimensional development of the mixed layers being described

the quasiordering properties of the structures concerning the flow direction vortex and the expand direction vortex during the evolution process being analysed. In order to verify the accuracy and reliabllity of direct numerical simulation for the mixed layer turbulence

a comparison of the flow field simulation results with the experiment results obtained by our predecessors has been made

the flow quantities

such as the pulsating velocity of flow direction vortex turbulence

the thickness of vorticity in mixed layer etc.

being compared. The numerical calculation tallies well with the experimental results of our predecessors

proving the accuracy and reliability of the direct numerical simulation method.