Determination of Fluid Damping Using Random Excitation

An experimental investigation has been carried out to verify the validity of the use of the random decrement technique to determine the damping coefficients for a circular cylinder oscillating in water. Data are reported for amplitudes ranging from 0.4 diameters to 0.8 diameters, for water speeds from zero to 0.192 m/s (0.63 ft/sec), and for frequencies ranging from 0.37 Hz to 1.4 Hz. Comparison with other data, which has been reported in the literature or obtained by the authors, shows that the random decrement method yields comparable damping coefficients to those obtained using the logarithmic decrement technique for the range of variables in this experiment.