Measurement of Drag Coefficient for an Elliptical Cylinder

P Sooraj; Amit Agrawal; Atul Sharma

Authors

P Sooraj Department of Mechanical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 0076, India
Amit Agrawal Department of Mechanical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 0076, India
Atul Sharma Department of Mechanical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 0076, India

Keywords:

PIV, Drag coefficient, Modified Wake Survey Method

Abstract

This paper reports drag coefficient for an elliptic cylinder as obtained from PIV measurements. We first evaluate three different methods to obtain drag force on an object immersed in a flow using particle image velocimetry (PIV) data, but no additional input data. The need for such a study is felt because PIV does not directly yield pressure-field required in the calculation of drag. The methods are benchmarked against circular cylinder. The three methods yield the values of drag coefficient within 1%. The method is further applied to elliptic cylinder over a large range of Reynolds number (Re = 240 – 34,000). The value for drag coefficient for elliptic cylinder over this range is not readily available. A sensitivity analysis of the result on the size of the observation window is also provided; the results indicate that reliable results are obtained if the viewframe is located at least 2.7 C downstream and 1.1 C on either
lateral side of the cylinder. The methods evaluated here can be further employed with PIV data for various flow problems.