Wave-Induced Drift of Large Floating Objects in Regular Waves

The current study experimentally investigates the wave-induced drift velocity of two-dimensional large floating objects (with $Lg/L>0.2$, where $Lg$ = longitudinal length of the floating objects, and $L$ = wavelength) under the action of regular waves. The focus is on the high-precision measurement of drift behavior and a wider range of parameters than what was previously reported in the literature. Stacked wood pieces with various submergences ($s$) were used to simulate the large floating objects on the water surface. An infrared-based motion monitoring system with two high-resolution cameras continuously recorded their motion in regular waves. The results show that the drift velocity increased quickly from the beginning and reached a quasi-steady mean value. The magnitude of the quasi-steady drift velocity increased with ratio of the pitch period to the wave period ($T_R/T$), until reaching a maximum when $T_R/T\approx 1$. After that, further increasing the ratio of $T_R/T$ did not lead to additional significant changes in the drift velocity. Three nondimensional submergences ($s/Lg$) of 0.0075, 0.022, and 0.036 were examined. The drift velocity typically decreased with larger submergence, which can be attributed to the larger added mass involved in the oscillatory motion.