Turbulent boundary layer flow over two side-by-side wall-mounted cylinders: Wake characteristics and aerodynamic loads.

Experimental investigation of distinctive wake characteristics and aerodynamic loads was conducted for two wall mounted side-by-side cylinders with varying gap distances. The results indicate that with decreasing gap wake recovery can be effectively delayed as the upwash and downwash flows from top and bottom ends of cylinders are suppressed. In general, at smaller gaps, turbulence intensity levels increased at the top ends of cylinders due to strong local velocity shear. Integral time scales distribution along mid-span of the cylinder shows that local recirculation flows in the near wake region highly influence velocity fluctuations, whereas at the top end, mixing of boundary layer flows dominate them. Lift and drag force coefficients calculated by considering equivalent velocity along cylinder span show no deviation from “infinite length” cylinder case. However, unlike infinite cylinders, there was no clear intermittency of aerodynamic loads observed as three-dimensional flow effects and strong background turbulence suppress two-dimensional vortex shedding. Joint PDF distribution indicate that drag force coefficient remains unaffected by cylinder gaps but lift coefficients fluctuate stronger with growth of gap distances.