Open Access

ARTICLE

Steady Separated Flow Past Elliptic Cylinders Using a Stabilized Finite-Element Method

Subhankar Sen¹, Sanjay Mittal², Gautam Biswas¹

1 Department of Mechanical Engineering, Indian Institute of Technology Kanpur, India
2 Department of Aerospace Engineering, Indian Institute of Technology Kanpur, India

Computer Modeling in Engineering & Sciences 2012, 86(1), 1-28. https://doi.org/10.3970/cmes.2012.086.001

Abstract

The steady flow around elliptic cylinders is investigated using a stabilized finite-element method. The Reynolds number, Re, is based on cylinder major axis and free-stream speed. Results are presented for Re ≤ 40 and 0° ≤ α ≤ 90°, where α is angle of attack. Cylinder aspect ratios, AR considered are 0.2 (thin), 0.5, 0.8 (thick) and 1.0. Results for the laminar separation Reynolds number, Re_s available in the literature are only for thin cylinder and exhibit large scatter. Also, very limited information is available for separation angle. The present study attempts to provide this data. In addition, issues concerning initial separation, such as location of separation and its evolution with α and Re, are studied. Symmetric cylinders are associated with a closed wake and consists of two attached eddies which appear at Re_s. Wake topology for asymmetric separation is proposed and compared with those of Smith (1983) and Dennis and Young (2003). The proposed topology differs significantly from the existing ones. For asymmetric cylinders, the wake is open and consists of an attached upper bubble and an unattached recirculation zone. The attached bubble appears at Re_s while the unattached zone appears at a larger Re. While symmetric separation initiates from base point, bubbles for asymmetric separation form near the trailing tip of thin and center of thick cylinders. For symmetric cylinders, the bubble elongates, approximately, linearly with Re. Irrespective of AR, Re_s exhibits non-monotonic variation with α.

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Keywords

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