Concentration distribution in an open channel flow by observational approach

Abstract

This study presents empirical models for two different types of suspended sediment concentration distribution in vertical direction for straight rectangular open channel flow. Initially, asymptotic solutions for inner and outer suspension regions are proposed by observing the data patterns; and finally, analytical models are developed by applying Guo’s logarithmic matching method. As a consequence, it is found that the volumetric sediment concentration is best expressed by a logarithmic law for type I profile (maximum concentration appears at the channel bottom) and by a power law for type II profile (maximum concentration appears at some distance above channel bottom) throughout the flow depth. Models are compared with existing models and experimental data and fairly good agreement is obtained in each case. The effects of sediment concentration on model parameters are also studied, and their variations are expressed by empirical relations.

Keywords:

• open channel turbulent flow
• suspended sediment concentration distribution (SSCD)
• logarithmic matching
• inter-particle collisions
• viscous sub-layer

Subject classification codes, MSC 2010:

• 76F25
• 76R50
• 76T20