Flow over a symmetrically curved circular cylinder with the free stream parallel to the plane of curvature at low Reynolds number

Abstract

Three-dimensional flow past a symmetrically curved circular cylinder with the free stream parallel to the plane of curvature is numerically investigated by high-order spectral element method. The axial line of the cylinder is described in Cartesian coordinates as y=A[cosh(x∕A)−1] with A being a catenary coefficient used to scale its span ratio. In this geometry configuration, the deformed cylinder can be divided into two half segments, respectively of the convex segment in the upstream and the concave segment in the downstream. Different span ratios are investigated with respect to A=0.5∼10. It is found that four wake topologies, namely of single body, bi-stable, vortex impingement and steady wakes, are successively appeared with the increase of the span ratio. By examining the flow field quantities including mean and fluctuation of velocities and pressure along the axial line, some important characteristics of axial flow dynamics are intensively revealed. Most interestingly, the generation of axial flow along the curved surface of the cylinder is strongly influenced by not only the curvature ratio but also the wake interference effects.