A. Jahangir - Department of Water science and Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
K. Esmaili - Department of Water science and Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
M. F. Maghrebi - 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 ۲۲ and ۱۹%, respectively. In all experiments, the cavity trapping rates of ۰.۱۳% and ۰.۱۴% at ۱۰% and ۲۰% 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 ۰.۹۹۵ and ۰.۹۸۱ 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 ۳.۶۲% higher than that in the groove. For the increased thickness with ۱۰% 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 ۲.۲۵ m from the first one.

Density current, Obstacle porosity, Obstacle installation angle, Obstacle thickness, Second layer of obstacle, Permeable obstacle