FLUID FORCES ON A CYLINDER OSCILLATING IN LINE WITH A UNIFORM FLOW

An experimental investigation has been made of the fluid forces acting on a circular cylinder oscillating in line with a uniform flow. The in-line forces were determined from measurements of the ensemble-averaged, cyclic pressure-distribution. The Morison equation, together with the least square method, was then used to evaluate the hydrodynamic coefficients of drag and inertia. Measurements of the drag coefficient are presented for large reduced velocities from 20 to 110, and Keulegan-Carpenter number from 2.5 to 15. It was found that the inertia coefficient at large reduced velocities, up to about 100, could be determined from the Morison equation provided the Keulegan-Carpenter number has a large value of about 15.