in the computational fluid dynamics (cfd) modeling of gas-solids two phase flow, the effect of boundary conditions play an important role in predicting the hydrodynamic characteristics of fluidized beds. in this work, the hydrodynamics of conical fluidized bed containing dried tio2 nano-agglomerates were studied both experimentally and computationally. the pressure drop was obtained by pressure...

The development of particle-enriched regions (bed-load) at the base of particle-laden gravity currents has been widely observed, yet the controls and relative partitioning of material into the bed-load is poorly understood. We examine particle-laden gravity currents whose initial mixture (particle and fluid) density is greater than the ambient fluid, but whose interstitial fluid density is less...

Bottom boundary layer effects on the linear wave propagation over mild slope bottoms are analyzed. A modifiedWKB approximation is presented including boundary layer effects. Within the boundary layer, two cases are considered: laminar (constant viscosity) and turbulent. Boundary layer effects are introduced by coupling the velocity inside the boundary layer to the irrotational velocity in the c...

Waters flowing in natural streams and rivers have the ability to scour and to deposit materials, hence to change the bed topography. It is recognized that undular flows have great potential for sediment transport. In the present study, a fixed-bed model was used to investigate the spatial variations of boundary shear stress under standing waves (i.e., undular flow). The results (Figure 8) highl...

-In this paper, the transient forced convective condensing flow of a gas through a packed bed is analyzed. The model developed for this analysis does not employ any local thermal equilibrium assumption between the solid and the fluid phases. Inertial as well as viscous effects are considered in the vapor phase momentum equation by using the Ergun-Forchheimer relation. Thermal charging of the pa...

[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...

abstract for investigating the effect of bed form in alluvial channels on the amount of bed load transport, a set of experiments was carried out in a tilting flume under unsteady flow conditions (hydrograph). the produced hydrographs were in triangular form with a maximum discharge of 30 to 45 lit/s/m. three size of sediment particles were used with equal to 1.5, 2.1 and 3.0mm, clear water with...

We present results from laboratory experiments in a wave flume with and without a sediment bed to investigate the turbulent structure and sediment dynamics of wave-supported mud layers. The presence of sediment on the bed significantly alters the structure of the wave boundary layer relative to that observed in the absence of sediment, increasing the TKE by more than a factor of 3 at low wave o...