Influence of geometrical arrangement of piles on morphology around permeable groyne

In this study, the bed topography changes around a single and two-rows opened groins ‎experimentally studied. The experiments carried out for different percentages of opening, different ‎distances of two rows of rods and differents Froude Numbers. The two-row rods groins considered ‎by two geometrical arrangement, in one condition the two rows of rods of opened groin placed ‎Zigzag and, in the other case, the two-row rods placed along with each other. The results showed ‎that the effect of increasing the Froude number on the maximum scour depth in the case of two-‎row along each other groin is greater than zigzag. So, As the Froude number increases from 0.22 to ‎‎0.3, the maximum scour depth in the two-row along each other case becomes 86% more than the ‎zigzag groin. The results also show that for different per cent of opening, the maximum scours ‎depth in the two-row along each other is about 85% more than the zigzag groin. However, as the ‎percentage of openness decreases from 70% to 30% in the two-step open breakwater, the Zigzag ‎rate of increase of the maximum scour depth is almost the same.‎