1. The influence of hydraulic conditions on the spatial distribution of macroinvertebrate assemblages was investigated in three riffles in a perennial Australian river. 2. Velocity, depth and variability of substrate roughness were measured at each of 56 macroinvertebrate sampling locations. Complex hydraulic variables (roughness Reynolds number, shear velocity, Froude number) were calculated f...

A negative surge is an unsteady open channel flow characterised by a drop in water surface elevation. In this study, a negative surge generated by the rapid gate opening was investigated experimentally with three types of bed roughness. Both instantaneous free-surface and velocity measurements were performed and the results were ensemble-averaged. The experimental data showed a rapid flow accel...

The powder bed surface roughness plays an important role in the quality of final parts fabricated using Additive Manufacturing processes. This paper reports development and application a new technique prototype instrument which can be used to simulate creation reveal properties that bed. tester was successfully study roughness, but also evaluate relative packing fraction, change particle size s...

Mountainous river beds-generally consist of gravel particles that the precise description of such bed is not only important hydraulically, but also it has great environmental significance. The accurate estimation of bed roughness gives us valuable information to make reliable hydraulic models of flow in river with rigorous bed form. This study discuses about the accuracy of the Kinect device in...

This study experimentally investigates the effect of a bumpy base on the Brazil-nut phenomenon in a vertically vibrated granular bed. The rise dynamics of an intruder is determined by the particle tracking method. The results indicate that the rise time increases with an increase in the base roughness, and the variation of the rise time with different base factors is more pronounced with smalle...

In open channels and water supply canals, the brusque operation of control valves and gates may induce large unsteady flow motions called surges. To date, the literature has focused on the propagation of surges in smooth canals, ignoring the effects of large roughness and debris. Herein, a physical study was conducted under controlled flow conditions to study the turbulent mixing in the close v...

[1] A new method has been developed that models the changes a wave-formed rippled sediment bed undergoes as it is actively evolving between two given equilibrium states due to a change in surface wave conditions. The transient analysis of rippled beds has received very little attention within the literature. Dynamic changes within ripple parameters have implications for the estimation of flow d...

Natural bedrock rivers flow in self-formed channels and form diverse erosional morphologies. The parameters that collectively define channel morphology (e.g. width, slope, bed roughness, bedrock exposure, sediment size distribution) all influence river incision rates and dynamically adjust in poorly understood ways to imposed fluid and sediment fluxes. To explore the mechanics of river incision...

abstract in all river engineering projects, determination of flow resistance is essential. most commonly, the manning roughness coefficient, , is used to describe the flow resistance or relative roughness of main channel or flood plane. over the past decades little or no study has been conducted to investigate the effects of particle shapes on manning roughness coefficient. therefore, it is the...

[1] Bed surface coarsening was found to be an important effect for the formation of ripples and the dynamics of the boundary layer above a predominantly silt-sized sediment bed (median particle size equal to 26 mm; 20% fine sand, 70% silt, 10% clay) under oscillatory flow (with orbital velocities of 0.32–0.52 m/s) in a laboratory wave duct. Following bed liquefaction, substantial winnowing of t...