Wave generation due to partially and completely submerged column collapse

The present study explores the wave generation, progression, and decay induced by the collapse of partially/completely submerged granular columns in a confined domain. The wave reflection at the opposite side of the landslide becomes important, especially in reservoirs of narrow width, leading to the consideration of a confined experimental setup. The time history of the waves recorded at fixed spatial points within the domain is characterized by the peak amplitude, time of arrival and decay. The non-dimensional peak amplitude for the same granular heights varies inversely with the fluid depth. The maximum wave amplitude is recorded at the downstream boundary, and the decay of the waves follows an exponential law that becomes asymptotic to the mean water level. The decay coefficient of the exponential law for partially submerged cases depicts that the water surface fluctuations die down faster in the middle than in the downstream extremity and near the collapse zone. For fully submerged cases, the faster dissipation is observed near the toe of the collapse zone. The post-collapse interaction of the waves with a sloping porous surface leads to a slowed dissipation of the waves in the domain and sometimes induces secondary granular motion as well.