Scour Caused by Propeller Jet Flow on Clay/Sand Mixture Seabed near Vertical Quay Wall

This study presents an experimental investigation of seabed scour in front of a quay wall due to the interaction between propeller jet flow and the wall effect. For this purpose, two propellers (Dp = 6 and 9 cm in diameter) were used, and four different wall clearances (Xw = 2, 4, 6 and 8Dp) were selected. The experiments were carried out for propeller rotational speeds ranging from 300 rpm to 1000 rpm. The effect of clay content was also investigated using three different clay contents of 0, 5 and 10% by weight (i.e., p = 0, 0.05 and 0.1). The results of the study reveal that at low propeller rotational speeds, scour in the cohesive seabed is decreased compared to that in the cohesionless bed. The scour profiles obtained at high propeller rotational speeds for the seabed with a clay content of 5% were found to have the same characteristics as those obtained for the cohesionless seabed. However, as the clay content increases to 10%, significant changes occur in the scour profiles, and the cohesion effect begins to dominate.