Flow past a circular cylinder at low Reynolds number: Oblique vortex shedding

Oblique shedding in the laminar regime for the flow past a nominally two-dimensional circular cylinder has been investigated numerically via a stabilized finite element method. No-slip condition on one of the sidewalls leads to the formation of a boundary layer which promotes oblique vortex shedding. Computations are carried out for three values of Reynolds number (Re): 60, 100, and 150. Cellular shedding is observed in all cases. Three cells are observed along the span for the Re=60 flow while only two cells are formed at Re=100 and 150. Spotlike vortex dislocations form at the junction of the cells. The frequency of the appearance of the dislocations increases with Re. Cellular shedding leads to low frequency modulation in the time histories of aerodynamic coefficients. Lowest value of drag is achieved at a time instant corresponding to the appearance of a new dislocation in the near wake. The vortex shedding frequency as well as the oblique angle of the primary vortices is found to vary with time for t...

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