Impact of Aspect Ratio on Drag and Flow Structure for Cylinders With Two Free Ends

Abstract When examining the literature for flow effects on circular cylinders one can find many studies on infinite cylinders and cantilevered cylinders but minimal data related to cylinders with two free ends (Shepard, T., Law, D., Dahl, J., Reichstadt, R., and Selvamani, A. S., 2022, “Impact of Aspect Ratio on Drag and Flow Structure for Cylinders With Two Free Ends,” ASME Paper No. V001T03A031.). The limited data available shows that the cylinder aspect ratio affects the drag and frequency content of flow within the wake however these studies were done at discreet Reynolds numbers. In order to better understand the combined impact of aspect ratio and Reynolds number a series of wind tunnel tests and numerical simulations has been conducted for cylinders with two free ends having aspect ratios of 2–15. Tests were carried out in the subcritical regime with Reynolds numbers ranging 13000–105,000. Tip vortex effects, which vary with aspect ratio, are shown to impact the cylinder surface pressure, drag coefficient, and wake Strouhal numbers though Reynolds number effects are minor for the conditions studied. The results are compared against existing historical data and show the trend of drag coefficient increasing with cylinder aspect ratio (Shepard, T., Law, D., Dahl, J., Reichstadt, R., and Selvamani, A. S., 2022, “Impact of Aspect Ratio on Drag and Flow Structure for Cylinders With Two Free Ends,” ASME Paper No. V001T03A031).