Stability boundaries for vortex breakdowns and boundaries between oscillatory and steady swirling flow in a cylindrical annulus with a top rotating lid
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The present numerical simulation is carried out to analyze the behaviors of vortex breakdown in a lid-driven swirling flow in cylindrical cavity with a thin axial stationary or rotating rod. The range of aspect ratio (AR) of the cavity considered is to be from 1.0 to 2.5. However, Reynolds number (Re) value, for a given AR, ranges from 1000 to any value till the topmost point on the boundary of steady vortex breakdown zone is achieved. This enclosed flow region is also referred as annulus cylindrical cavity. A systematic study has been carried out involving a large number of simulations to obtain one-vortex or two-vortex breakdown zones for steady lid-driven swirling flow in the annulus cylindrical cavity. Cases within the inner wall, i.e., the axial rod being stationary or rotating, have been considered. It is observed that the boundaries of zones and of vortex breakdowns shift due to the presence of stationary/co-rotating thin axial rod. These zones of vortex breakdowns are represented with plots in AR–Re plane for various rotating speeds of the axial rod. These plots give quick information regarding overall influence of the presence of the thin axial rod. The direction of rotation of the rod is important; the co-rotating rod has stabilizing effects, whereas counter-rotating rod tends to create unsteady flow.
KeywordsSwirling flow Axisymmetric Incompressible
Authors are very much thankful to Aerospace Engineering Department, IIT, Kharagpur, West Bengal, India, and Jaypee University of Engineering and Technology, GUNA, MP, India, for giving facility to conduct the research work.
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