Forced convection past a semi-circular cylinder at incidence with a downstream circular cylinder: Thermofluidic transport and stability analysis

Abstract

The present study analyzes the transport characteristics and associated instability of a forced convective flow past a semi-circular cylinder at incidence with a downstream circular cylinder. Considering air as an operating fluid, unsteady computations are performed for the ranges of incidence angles φ and Reynolds numbers (Re) (0° ≤ φ ≤ 90°, 60 ≤ Re ≤ 160). The numerical model is adequately validated with the available experimental and numerical data from the literature. It is found that the presence of the upstream semi-circular cylinder at various incidence angles yields a rotational effect on the flow structures that evolve from the downstream circular cylinder. The modulation of the incidence angle reveals three separation regimes of the shed-vortex structures, which shows wake confluence. The dependencies of the coefficient of drag C D and the root mean square values of the lift coefficient C L, r m s on the angles of incidence are examined for both of the cylinders. The frequency of vortex shedding increases with increasing φ and attains its peak value at φ ∼30°. The forced convective heat transfer for the semi-circular cylinder decreases with increasing φ, whereas a contrasting trend is observed for the circular cylinder until φ ∼45°. The global stability analysis through the dynamic mode decomposition shows a stabilizing flow situation for the present range of operating parameters.