Author(s): Caroline Ubing; Robert Ettema; Christopher I. Thornton
Keywords: Energy loss; flow–structure interactions; hydraulic resistance; laboratory study; open channel flow
Abstract: Presented are the results of flume experiments on the flow-retarding performance of baffle-post structures in openwater flow. Such structures consist of one to two parallel rows of unsubmerged posts that retard an approach flow, reducing flow velocity, increasing flow depth, and altering lateral distribution of flow. The results relate headloss and flow depth increase at the structure to lateral and streamwise variations in post spacing, post diameter, and approach flow conditions, and represent average velocities of flow through the structure. For given approach flows, the flow-retarding performance of baffle-post structures is shown to be much more sensitive to lateral spacing of posts and approach flow Froude number, than to streamwise spacing (for double row structures) and approach-flow depth relative to post diameter. Estimates are given for the percentage increase in water depth that baffle posts will produce. This information informs the design of baffle-post structures and evaluation of the backwater effect.