Author(s): Vajapeyam S. Srinivasan; Hugo M. Alcantara; Valter R. G. Medeiros
Linked Author(s): Vajapeyam S. Srinivasan
Keywords: Lluvial channels; Resistance to flow; Effect of grain size distribution
Abstract: This paper presents an analytical and experimental study of the influence of the grain size distribution within the bed sediment mixtures on the hydraulic resistance of erodible bed channels. The experimental investigation considers both unimodal and bimodal sediment mixtures. Based on the resistance law for a rough surface, a new simple functional relationship is defined that takes into account the form roughness of each type of bed form separately. This functional relationship was established experimentally for three different mixtures of unimodal sediments that had the same mean diameters but different grain size distributions, as well as, three different bimodal mixtures with different mean sizes. The experiments were conducted in a recirculating laboratory flume. The results show that the size distribution and the nature of the sediment mixture affect the resistance relationship. The proposed functions have the advantage of not necessitating the separation of total roughness as surface roughness and form roughness.
Year: 2007