I discussed a master's thesis at the College of Engineering at the University of Basrah (a numerical study of an unstable stratigraphic flow through a three-dimensional channel with sudden expansion)

The thesis presented by the student Ahmed Nissan Nayef included the use of the ANSYS FLUENT 15.0 program to solve the equation of conservation of momentum and continuity using the method of finite volumes to convert equations from differential equations to algebraic equations, which can be solved based on the simple procedure SIMBLE where the results are presented in the form of diagrams with a discussion of all variables such as velocity components The intensity of the turbulence, the pressure drop, the limits of the backflow area and the state of the flow within the channels

The thesis aims at a numerical study of a laminar flow unstable with time passing through a canal with sudden expansion in cross-sectional area.

The thesis concluded that an increase in both Reynolds number (Re) and aspect ratio AR leads to an increase in the time to reach stability, that is, we need more time to reach stability, and this effect is more pronounced at high values ​​of Reynolds number (Re>1000). A significant effect on the instability of the variables, and this effect is not observed at the few digits of the Reynolds number