Numerical Simulation of the Flow Around an Infinitely Long Circular Cylinder in the Transition Regime |
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Authors: | Oliver Posdziech Roger Grundmann |
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Institution: | (1) Institute for Aerospace Engineering, Dresden University of Technology, 01062 Dresden, Germany posdzie@tfd.mw.tu-dresden.de, DE |
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Abstract: | The development of three-dimensional structures and the succeeding transition to turbulence occurs in the wake of a circular
cylinder at Reynolds numbers 190≤Re≤330. This regime is investigated numerically by means of a spectral element method. Earlier numerical works aimed mainly
at reproducing characteristic wake patterns observed in experiments. Small sizes of computational domains and short integration
times were chosen to save computational resources. Consequently, the quantitative results show a considerable scatter. Within
this work, a step by step approach to highly accurate direct numerical simulations is described. Thorough studies of the effect
of resolution and blockage are performed in the laminar, two-dimensional regime, resulting in Reynolds number relationships
that exactly reproduce experimental data. Based on these results, a stability analysis is performed to obtain wavelengths
that are unstable against spanwise perturbations and the critical Reynolds number for the onset of three-dimensionality. The
most unstable wavelengths of the “mode A” and “mode B” instabilities and its multiples are used as periodicity length for
direct numerical simulations. Effects of integration time, resolution in streamwise as well as spanwise directions, and periodicity
length on the flow quantities are studied. Numerically obtained Reynolds number relationships of Strouhal number and base-pressure
coefficients that fit accurately within measured results are given for the first time. Curves for drag and lift coefficients
are provided and compared with previous numerical studies. Furthermore, physical interpretations of the wake transition are
discussed. Since the separation of physical features and effects of experimental arrangements are frequently an open question,
our numerical results are able to supply a contribution to the understanding of the physics of cylinder flow.
Received 12 September 2000 and accepted 26 June 2001 |
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