Large-Scale Roughness in Open-Channel Flow

A new method of predicting resistance to flow in open channels with large roughness elements is proposed. The roughness elements investigated consisted of 6-in. and 3.75-in. cubes; these were arranged in a variety of symmetric and random patterns. The majority of patterns used 6-in. cubes and one random pattern included both 6-in. and 3.75-in. cubes. It was found that systematic relationships do exist among the Manning's n, Reynolds Number, Froude Number, and a special quantitative parameter of the roughness pattern.