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LARGE EDDY SIMULATION STUDY OF A WALL-INDUCED PERTURBATION OF VORTEX SHEDDING FROM A SQUARE CYLINDER

Miodrag Darko Matovic
Department of Mechanical Engineering, Queen's University Kingston, Ontario, Canada, K7L 3N6

Robert J. Martinuzzi
Department of Mechanical and Manufacturing Engineering Schulich School of Engineering, University of Calgary 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4

Résumé

The turbulent flow field around a square cross-section cylinder mounted near a solid wall has been simulated using Large Eddy Simulation. Critical and sub-critical cylinder-towall separations are investigated. The three-dimensional nature of the base region flow is well resolved by the multiblock grid system employed. It is shown that for both regimes, the interaction between shear layer and the vorticity generated along the wall in the wake can give rise to periodic wake fluctuations without the traditional vortex formation and shedding process. The results are shown to be consistent with experimental observations. This paper focuses on the vorticity dynamics in the gap and post-gap region along the wall and their role as a "surrogate" generators of vortex shedding. While there is clear quantitative difference between the two cases, namely much higher periodicity in a critical case, the two cases reveal essentially the same shedding mechanisms.