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Effects of size and position of upstream cylinder on wake transition in flow past two in-line square cylinders
Published in Begell House Inc.
Volume: 27
Issue: 2
Pages: 143 - 184
Two-dimensional numerical investigations of flow past two inline stationary square cylinders con-fined in a rectangular channel have been carried out using finite volume-based commercial software ANSYS Fluent 17.2. The flow field characteristics have been studied at different values of inter-cylinder spacing (S), flow Reynolds number (Re), and size ratio (SR is the ratio of side length of upstream cylinder to that of downstream cylinder). Effects of S, Re, and SR on the flow behavior in upstream and downstream wakes have been presented using vorticity contours. Critical Reynolds number for the onset of planar vortex shedding behind the downstream cylinder has been reported for different values of S and SR. It has been noted that wake transition behind the downstream cylinder depends on the values of S and SR, and the onset of unsteadiness gets delayed with increase in the size of the upstream cylinder for a given intercylinder spacing. Three different shedding modes, viz., single slender body, reattachment mode, and binary mode, have been illustrated using vorticity contours. Temporal wake oscillations have been examined using Hilbert–Huang transfor-mation of time varying signals of force coefficient. Extent of nonlinear interactions and their effect on frequency distribution have been presented in the Hilbert and marginal spectra and quantified in terms of the degree of stationarity. Variation in lift and drag coefficients on upstream and downstream cylinders has also been reported for different values of Re, S, and SR. © 2020 by Begell House, Inc.
About the journal
JournalData powered by TypesetJournal of Flow Visualization and Image Processing
PublisherData powered by TypesetBegell House Inc.
Open AccessNo