Abstract
The unsteady flow behaviours at the interface between the main flow and the dead zone area in open channels are investigated both experimentally and numerically. The vortex formation processes in the mixing layer between two flow regions (main flow and dead zone) are reproduced numerically by means of the 2 D plane open channel flow equations in the variable grid system. It will be pointed out through the comparison of the numerical results to the laboratory tests that the velocity fluctuations can be decomposed into the two components due to the seiche and the shear layer instability and that the later component is amplified to the large scale vortex, as shown in the photograph of visualization, when the resonance of both components occurs.
