Search results for "LOCI"
showing 10 items of 1277 documents
Flow resistance in mobile bed rills shaped in soils with different texture
2021
Rill erosion is considered one of the most important soil processes because of the large amount of soil loss due to the development of a rill network able to promote an efficient transport of both rill flow-detached particles and those delivered from the inter-rill areas. Rill flow experiments are useful to overcome the gap in rill hydraulics knowledge and to test the reliability of currently applied uniform open channel flow equations for mobile bed rills. In this paper the applicability of a theoretical flow resistance equation, based on a power-velocity profile, to rill channels shaped on soils having different textures was investigated. The measurements (437 runs) of water depth, cross-…
Applying Hypothesis of Self-Similarity for Flow-Resistance Law in Calabrian Gravel-Bed Rivers
2018
In this paper, the results of an investigation carried out to test the applicability of a flow-resistance law on gravel-bed rivers in southern Italy (fiumare) are reported. First, dimensional analysis and self-similarity theory are applied for deducing the flow-resistance law (i.e., relationship among friction factor, mean velocity, shear stress, and physical properties) for gravel-bed rivers with a high boulder concentration. The proposed approach is calibrated and tested using two independent data sets (104 reaches of some Calabrian fiumare). Then, the incomplete self-similarity hypothesis is also applied to theoretically deduce the flow-velocity profile, which was integrated for obtainin…
Rill flow resistance law under sediment transport
2021
Abstract Purpose In this paper, a deduced flow resistance equation for open-channel flow was tested using measurements carried out in mobile bed rills with sediment-laden flows and fixed bed rills. The main aims were to (i) assess the effect of sediment transport on rill flow resistance, and (ii) test the slope-flow velocity relationship in fixed bed rills. Methods The following analysis was developed: (i) a relationship between the Γ function of the velocity profile, the rill slope and the Froude number was calibrated using measurements carried out on fixed bed rills; (ii) the component of Darcy-Weisbach friction factor due to sediment transport was deduced using the corresponding measurem…
Rill flow resistance law under equilibrium bed‐load transport conditions
2019
In this paper, a recently deduced flow resistance equation for open channel flow was tested under equilibrium bed-load transport conditions in a rill. First, the flow resistance equation was deduced applying dimensional analysis and the incomplete self-similarity condition for the flow velocity distribution. Then, the following steps were carried out for developing the analysis: (a) a relationship (Equation) between the Γ function of the velocity profile, the rill slope, and the Froude number was calibrated by the available measurements by Jiang et al.; (b) a relationship (Equation) between the Γ function, the rill slope, the Shields number, and the Froude number was calibrated by the same …
Testing slope effect on flow resistance equation for mobile bed rills
2018
In this paper, a recently theoretically deduced rill flow resistance equation, based on a power-velocity profile, is tested experimentally on plots of varying slopes in which mobile bed rills are incised. Initially, measurements of flow velocity, water depth, cross-sectional area, wetted perimeter and bed slope conducted in 106 reaches of rills incised on an experimental plot having a slope of 14% were used to calibrate the flow resistance equation. Then, the relationship between the velocity profile parameter Î, the channel slope, and the flow Froude number, which was calibrated using the 106 rill reach data, was tested using measurements carried out in plots having slopes of 22% and 9%. …
Velocity measurements in the liquid metal flow driven by a two-phase inductor
2012
We present the results of velocity measurements obtained by ultrasonic Doppler velocimetry and local potential probes in the flow of GaInSn eutectic melt driven by a two-phase inductor in a cylindrical container. This type of flow is expected in a recent modification to the floating zone technique for the growth of small-diameter single intermetallic compound crystals. We show that the flow structure can be changed from the typical two toroidal vortices to a single vortex by increasing the phase shift between the currents in the two coils from 0 to 90 degrees. The latter configuration is thought to be favourable for the growth of single crystals. The flow is also computed numerically and a …
A study of turbulent heat transfer in curved pipes by numerical simulation
2013
Abstract Turbulent heat transfer in curved pipes was studied by numerical simulation. Two curvatures δ (pipe radius a/curvature radius c) were considered, 0.1 and 0.3; results were also obtained for a straight pipe (δ = 0) for comparison purposes. A tract of pipe 5 diameters in length was chosen as the computational domain and was discretized by finite volume multiblock-structured grids of ∼5.3 × 106 hexahedral cells. Fully developed conditions were assumed; the friction velocity Reynolds number was 500, corresponding to bulk Reynolds numbers between 12 630 and ∼17 350 according to the curvature, while the Prandtl number was 0.86 (representative of saturated liquid water at 58 bar). Simulat…
Velocity Distribution and Dip Phenomenon in a Large Amplitude Meandering Channel
2020
The prediction of the velocity-dip, whereby the location of the maximum velocity occurs below the water surface, could be important for defining the flow pattern and the momentum transport processes. This study explores the dip-phenomenon in a high-curvature meandering bend. With the aid of data collected in a laboratory flume, the influence of the distance to the outer bank, the channel's curvature and the aspect ratio on the formation and position of the velocity-dip is investigated. Results show that, for the aspect ratios examined, a dip forms in the velocity profiles and its position varies along the bend as a function of the channel's curvature and the aspect ratio. Based on the measu…
Bio-predictive tablet disintegration: Effect of water diffusivity, fluid flow, food composition and test conditions
2013
Abstract Food intake may delay tablet disintegration. Current in vitro methods have little predictive potential to account for such effects. The effect of a variety of factors on the disintegration of immediate release tablets in the gastrointestinal tract has been identified. They include viscosity of the media, precipitation of food constituents on the surface of the tablet and reduction of water diffusivity in the media as well as changes in the hydrodynamics in the surrounding media of the solid dosage form. In order to improve the predictability of food affecting the disintegration of a dosage form, tablet disintegration in various types of a liquefied meal has been studied under stati…