Document Type : Original Article
Department of Water science and Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
Department of Civil Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
This study explored the effect of porosity and installation angle, thickness (dimension) and second layer of permeable obstacles on density current control and trapping in the laboratory. For this purpose, an insoluble suspended polymer and two types of groove and cavity obstacles made from plexiglass sheets were selected. The experiments were conducted with two different concentrations, five different porosities, four different angles, four different thicknesses and two obstacle layers. The results showed that the optimum porosities for cavity and groove obstacles were 22 and 19%, respectively. In all experiments, the cavity trapping rates of 0.13% and 0.14% at 10% and 20% concentrations were higher than those of groove trapping. In addition, by increasing the angle, the rate of trapping decreased and its value was observed in the groove with the correlation coefficients of 0.995 and 0.981 compared to the cavity. The major effect of obstacles was found to be the flow deceleration where the average velocity in the cavity was obtained 3.62% higher than that in the groove. For the increased thickness with 10% porosity and groove type, the passage of materials from the obstacle further increased. By creating the second layer of obstacle, the passage of materials from the obstacle in the both groove and cavity increased, and the optimal distance of the second obstacle was 2.25 m from the first one.