# The Effect of Aspect Ratio on the Normal Force and Bending Moment Coefficients for a Surface-Mounted Finite Cylinder

## Abstract

A cylinder is constructed to have its aspect ratio (AR = *H/D*) varied between 0.5 and 11 in increments of 0.5. A force balance is used to measure a normal force developed on the free end of the cylinder, along with the drag force and corresponding bending moment. The forces are seen to be influenced by two critical aspect ratios, occurring at AR = 2.5 and AR = 6. The drag coefficient increases rapidly for low AR, is stable between the critical AR, and rises linearly for high AR. The normal force coefficient reaches a plateau between the critical AR. The bending moment coefficient and the point of action for the drag force are stable for AR higher than 6, and increase rapidly at low AR. Below AR = 2.5, the boundary layer is dominant, and above AR = 6, the free end effects begin to reduce as infinite cylinder behaviour is approached.

## Keywords

Fluid Bluff body Finite cylinder Drag Normal force Bending moment## References

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