Bottom racks have been widely used in dam-less projects as a means to divert some part of the river flow. Mesh-panel bottom rack is a new form of bottom rack which is introduced in this paper and consists of longitudinal bars along the river over transverse bars perpendicular to the river flow. Deformation of mesh-panel racks under static and dynamic loads is less than other kinds of bottom intakes. In the present study, firstly, physically-based relationships were derived for rack discharge coefficients in sediment and non-sediment flows. To do this, three mesh-panel racks were built, and the effects of hydraulic characteristics of approaching flow, rack geometry (slope, length, bar shapes), and sediment characteristics on discharge coefficient were investigated, and, also, a sensitivity analysis was taken. The data was obtained from a series of tests carried out in a laboratory flume equipped with inclined bottom rack and a sediment chamber at the upstream. For each run, diverted and remaining discharges were measured by two separate fully-aerated sharp crested rectangular weirs. Secondly, trap ratio of mesh-panel rack which was defined as the weight of passed sediment through the mesh, panel to the total input amount of sediment at upstream, were experimentally studied and discussed. Finally, a physically-based dimensionless relation for estimating trap ratio was presented, and sensitivity analysis was done. (C) 2017 Elsevier Inc. All rights reserved.
