Circular Cylinder Wake Configurations: A Flow Visualization Survey

The survey starts with the presentation of the general principles underlying the different types of techniques which are most often used in wake visualization with their advantages, but also their respective limits. Then information deduced from flow pictures collected from the literature from the beginning of the century up to the present has been used to characterize the wake structure of a circular cylinder (at rest or submitted to various motions) and its evolution with the Reynolds number for an extended range (0 < Re < 10⁷). Incompressible flow has been more particularly considered, both in the quasi-established phase (ten regimes are differentiated and extensively described) and in the transient phase (specific features are pointed out). Special attention has been paid to three-dimensional and memory effects by a combined presentation of crosswise and spanwise observations of the wake phenomena as well as their evolution with time. The influence of compressibility in the high-speed regime and of superimposed periodic motions, either on the cylinder or on the stream, have been also investigated and the main characteristics of the lock-in regime have been described. The survey is illustrated by 40 figures and completed by a table in which are reported the successive studies related to the flow around a circular cylinder based upon visualization, including a brief account of the experimental setups and methods, as well as a description of the main phenomena observed in the corresponding pictures.