Seagrass beds alter their hydrodynamic environment by inducing drag on the flow, thereby attenuating wave energy and near-bottom currents. This alters the turbulent structure and shear stresses within and around the seagrass bed that are responsible for the suspension and deposition of sediment. To quantify these interactions, velocity, pressure, and sediment measurements were obtained across a...

Erosion of intertidal sediments may be influenced by several factors. In this study, the influence on sediment erosion of some physical mechanisms such as the sediment bed roughness, suspended particles and surface waves was investigated. Because of the complexity of the phenomena involved, careful experiments have been planed in order to make each mechanism dominant and to assess its contribut...

Abstract Purpose Multimodal effective particle size distributions (EPSDs) develop as flocculation and breakage occur dynamically in a fluid shear such have been previously reported coastal estuarine waters to understand processes. Here, we use time varying multimodal EPSDs hydraulic parameters (discharge bed stress) assess freshwater gravel-bed river southern Alberta, Canada. Methods Instantane...

Contrary to what has recently been assumed in modeling the proposed eforming bed mechanism for the rapid motion of Antarctic ice streams, the rheology of water saturated till is probably highly nonlinear, according to information from soil mechanics and preliminary experiments on till from the base of Ice Stream B. The equivalent flow law exponent n is probably as high as ---100, and the nonlin...

We investigate the mechanics of ice streams and glaciers flowing over a bed consisting of Coulomb-plastic subglacial sediment, or more generally, of channel flows with Coulomb or ‘solid’ friction laws at the boundary. Sliding is assumed to occur if shear stress at the glacier bed attains a prescribed, locally defined yield stress, while no sliding is assumed possible below that yield stress. Im...

[1] Steep, rough channels occupy a large fraction of the total channel length in mountainous regions. Most sediment mobilized on hillslopes must pass through these streams before reaching lower-gradient channels. Steep channels have wide grain size distributions that are composed of finer, more mobile sediment and large, rarely mobile grains. The large grains can bear a significant portion of t...

In the food and pharmaceutical industries, the shear testing protocol developed by Jenike in 1964 has been commonly used to characterize powder flow. The protocol requires the measurement of the stress required to shear a powder bed under a series of normal consolidation stresses and the consolidated bulk density. In this work, we report the bulk density of thirteen milled lactose powders of di...

We reanalyze previous experimental measurements of solid volume fraction, mean velocity, and velocity fluctuations in collisional suspensions of plastic cylinders and water flowing over inclined, erodible beds. We show that the particle pressure scales with the granular temperature, as predicted by kinetic theory of granular gases. The assumption that the particle shear stress is also well pred...

We report laboratory determinations of the shear resistance to sliding melting ice with entrained particles over a hard, impermeable surface. With higher particle concentrations and larger particle sizes, Coulomb friction at particlebed contacts dominates and the shear stress increases linearly with normal load. We term this the sandy regime. When either particle concentration or particle size ...