Abstract
Vortex shedding from an inclined circular cylinder at low values of Reynolds number (Re) is investigated numerically. The aim of the study is to investigate the effect of cylinder oblique angle on the transition from two-dimensionality (2D) to three-dimensionality (3D) of the wake flow. The Navier-Stokes equations are solved by the Petrov-Galerkin finite element method for Reynolds numbers ranging from 100 to 1000 and the flow attack angles of alpha = 0 degrees and 45 degrees. For the right attack angle case (alpha = 0 degrees), the predicted wavy spanwise vortices in the early stage of the transition mode A, the vortex dislocation in the late stage of the transition mode A and the streamwise-vortex dominant wake flow structure in the transition mode B are found to agree well with independent experimental observations and measurements. The transition from 2D to 3D at alpha = 45 degrees. was found distinctively different from that at alpha = 0 degrees. For alpha = 45 degrees, no clear-cut transition modes are observed. The wake is characterized by wavy spanwise vortices close to the lower boundary of the transition Reynolds number regime, which are similar to those in the early stage of the transition mode A at alpha = 0 degrees. The vortex-dislocation in the transition mode A was not observed at alpha = 45 degrees. It appears that the fluid flow in the spanwise direction in the primary vortices at alpha = 45 degrees. does not allow the instability to sustain at a specific spanwise location and trigger the vortex dislocation. Although the wake flow structure is different, the variation of the normal Strouhal number with the normal Reynolds number (both based on the velocity component perpendicular to the cylinder span) at alpha = 45 degrees is close to that at alpha = 0 degrees in the transitional Reynolds number regime. The root mean square of the lift coefficient normalized by the velocity component perpendicular to the axial direction of the cylinder at alpha = 45 degrees is about 20% to 25% larger than that at alpha = 0 degrees in the Reynolds number regime between 250 and 500.
Original language | English |
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Article number | 14105 |
Number of pages | 20 |
Journal | Physics of Fluids |
Volume | 25 |
Issue number | 1 |
DOIs | |
Publication status | Published - 2013 |
Open Access - Access Right Statement
Copyright 2013 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Physics of Fluids (1994-present) 25, 014105 (2013) and may be found at 10.1063/1.4788934.Keywords
- dislocations
- dynamics
- length
- numerical simulation
- vortex shedding
- wake transition