The wake of two side-by-side elliptic cylinders

When two or more cylinder-like structures are placed in close proximity, the resulting interactions between the wakes are complex and known to alter the wake pattern significantly from those behind a single cylinder. One commonly investigated arrangement of two cylinders is the side-by-side configuration, wherein two identical cylinders are placed parallel to the incoming flow. In this work, we consider two oval-shaped (elliptical) cylinders with large values of eccentricities. The flow past these cylinders is studied experimentally in a water-tunnel setup by parametrically investigating the wake pattern for various values of gap ratio between the cylinders (0 - 2), Reynolds numbers (100 - 2000) and two eccentricity values. The three well-known wake regimes (single-body wake, asymmetric wake, two parallel wakes) are first quantified by dye visualization and then by planar Particle Image Velocimetry (PIV) technique. A bifurcation diagram, having the measured values of Strouhal numbers at specified locations in the wake and the gap ratios as coordinates, is presented, that identifies various wake modes of the side-by-side cylinders.