Fluid Impact Forces on Cylinders in Harmonic Flow.
Abstract
The evolution of forces acting on horizontal cylinders subjected to impact by an harmonically oscillating free surface has been investigated both theoretically and experimentally. The experiments were carried out in a large U-shaped water tunnel, with cylinder diameters ranging from 3.0 to 6.5 inches. The results have been expressed in terms of two force coefficients. The first is the slamming coefficient which expresses the normalized force acting on the cylinder at the time of impact; and the second is the maximum drag coefficient which occurs when the cylinder is immersed approximately 1.75 diameters in water. The slamming coefficient was found to be equal to pi, as predicted theoretically. It was also found that the slamming coefficient may be amplified to a value as high as 2 pi through the dynamic response of the cylinder. The maximum of the normalized force in the drag dominated region was found to be approximately equal to 2.0. It decreased with increasing Froude numbers to a value of about unity. It is recommended that further experiments be conducted with sand-roughened cylinders and the dependence of the rate of rise of the impact force on the flow parameters be investigated. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1977
- Accession Number
- ADA044324
Entities
People
- Richard A. Post
Organizations
- Naval Postgraduate School