Comparing the wake behind circular and elliptical cylinders in a uniform current

Abstract

In this study, an experimental investigation has been conducted on the characteristics of the wake behind the elliptical cylinder with the axis ratio of $AR=2$. In order to provide a comparison, the same experimental investigation has also been conducted for a circular cylinder with the vertical height equal to the height of the elliptical cylinder. For studying the wake behind these two cylinders, hot-wire anemometry measurement has been performed. All of the tests are carried out in Reynolds number of $3.0\times {10}^4$ (which is defined according to the mean velocity of air and the cylinder diameter). Results are presented in terms of time-averaged velocity, standard deviation, higher-order central moments of the hot-wire signals (skewness and kurtosis factors), Strouhal number and drag coefficient. For the regions near the wake, the velocity deficit of the elliptical cylinder is greater compared to the circular cylinder; however, this is completely reversed in the regions far from the wake. As the axis ratio of the cylinder decreases, the dimensionless standard deviation becomes higher, and it’s maximum value is located at an earlier stream-wise location. In addition, it is observed that by increasing the axis ratio of the cylinder, drag coefficient decreases, while the Strouhal number is increasing.