Numerical simulation of large scale vortex structure and flow pulsation in rectangular channels

The quasi periodic large scale vortex structure and flow pulsation in rectangular channels are investigated theoretically. Narrow gap or slot is not the necessary condition for the quasi periodic large scale vortex structure. The quasi periodic large scale vortex structure could be observed in flat rectangular channels with the same widths if appropriate velocity profile is available. The vortex structure and flow pulsation in velocity interface could be strengthened by the adjacent velocity interfaces. The effect of channel size on the vortex structure is significant. The quasi periodic large scale vortex structure and flow pulsation vanishes with the channel length decreasing. This work is helpful for the recognition of quasi periodic large scale vortex structure and strong turbulent mixing in rod bundles and channels.

► Narrow gap is not the necessary condition for large scale vortex structure.
► The large scale vortex structure could be observed in flat rectangular channels.
► The effect of channel size on the vortex structure is significant.
► The large scale vortex structure vanishes with the channel length decreasing.