Laboratory investigation of the effect of the number of bars on the performance of permeable groin: two radial absorbing and direct arrangements

In a laboratory study, a new arrangement for permeable groin has been presented in which the form and number of groin bars are different compared to the conventional direct form, and the effect of this new arrangement on the maximum depth of the scour hole was investigated at the groin nose. The permeability values of the groin group are considered equal to 40, 60 and 80% and the tests were performed in clear water conditions. The flow rate and bed conditions are considered the same in all tests and the behavior of groin to deal with local scouring of the nose under the change in permeability and the number of bars in the groin group in both radial absorbing and direct forms has been investigated and compared. The results show that among the tests conducted, the maximum depth of the erosion hole decreased with the increase in permeability, and also the performance of the provided radial absorbent arrangement is better and more effective than the direct arrangement in controlling the maximum depth of the erosion hole.