Application of logarithmic law to shallow open channel flows over large roughness

Abstract

In this research, the subsurface flow and regular open channel flow over large roughness are investigated. The flume setup had a channel bed consisted of gravel particles of d50 = 3.28cm with an average subsurface layer thickness of 10.6cm and bed slope of 0.0018.The Ergun equation (which is usually used in chemical engineering for describing the flow

resistance in porous media) was first investigated for its applicability in predicting the flow

discharge in the subsurface layer of an open channel. Volumetric measurement method was

used in the investigation of the subsurface discharge. Secondly, the logarithmic law was

investigated for its applicability in the regular open channel flow with H/d50 < 5 and large scale

roughness. Velocity measurements for the regular open channel flow were obtained from

particle image velocimetry measurements method.