Small-scale experiments on ice-jam initiation in a curved channel

1994 ◽  
Vol 21 (5) ◽  
pp. 719-727 ◽  
Author(s):  
Gilberto E. Urroz ◽  
Robert Ettema
Keyword(s):  
Froude Number ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Small Scale ◽  
Curved Channel ◽  
Point Bar ◽  
Ice Jams ◽  
Ice Jam ◽  
Point Bars ◽  
River Bends

Two principal ice-jam initiation mechanisms, namely, lodgement and gorging, were identified through ice conveyance experiments in a small-scale, curved flume of rectangular cross section. Polyethylene blocks and beads were used to simulate ice fragments. Lodgement occurred for ice fragments that were large relative to channel width, while gorging took place when ice pieces were relatively small and were transported through the channel in multilayer. Channel roughness was found to have a significant effect in helping the arching mechanism that produces lodging. Maximum ice-floe concentration before jamming was found to increase linearly with Froude number, F, when gorging was dominant, but showed little dependence on F for ice jams initiated by lodging. Experiments conducted with point bars placed at the bends indicated that ice jams were initiated mainly by beaching of floes on the point bar. Maximum ice-floe concentration also increased linearly with Froude number for the point-bar experiments. Key words: ice-covered rivers, river bends.

USE OF SPATIOTEMPORAL DIAGRAMS TO CHARACTERIZE A SILO DISCHARGING PROCESS

2013 ◽  
Vol 37 (1) ◽  
pp. 53-70
Author(s):  
Blaise Nsom ◽  
Noureddine Latrache
Keyword(s):  
Cross Section ◽  
Flow Rate ◽  
Mechanical Characterization ◽  
Direct Method ◽  
Rectangular Cross Section ◽  
Small Scale ◽  
Flat Bottom ◽  
Shear Box ◽  
A Direct Method

To get a better knowledge of discharging flows of ensiled granular materials, a small scale silo was designed and built. It is equipped with a flat bottom and it has a rectangular cross section. Moreover, it is entirely transparent for image processing purpose. First of all, a physical and mechanical characterization of wood granules (inert materials) was performed using a shear box testing. Then, silo emptying flows were generated. Flow regimes and flow rate were determined using spatiotemporal diagrams extracted from images of the free surface of the ensiled material. The same method was then used to measure the flow rate of discharging flows of soya, colza and rye seeds which were characterized in a previous study. For each material studied, the flow rate measured with this non intrusive method was successfully compared with a direct method consisting in weighing a volume of grains discharged during a unit time and with Berveloo’s formula.

On the Generation of Secondary Velocity Along a Vortex Line

1964 ◽  
Vol 86 (4) ◽  
pp. 815-818
Author(s):  
A. W. Marris
Keyword(s):  
Cross Section ◽  
Vortex Line ◽  
Rectangular Cross Section ◽  
Direct Action ◽  
Unsteady Flows ◽  
Curved Channel ◽  
Inviscid Flows ◽  
Convex Wall ◽  
Flow Phenomena ◽  
Secondary Velocity

A general expression for the generation of secondary velocity along a vortex line is developed for the case of incompressible flow with uniform viscosity. The result is given with various degrees of specialization, i.e., for unsteady flows, unsteady circulation-preserving flows, flows with vanishing flexion, and steady inviscid flows. The formulation for the case of steady flow in which the direct action of viscosity is discounted is applied to the rationalization of experimentally observed secondary-flow phenomena at the convex wall for entrance flow in a curved channel of rectangular cross section.

scholarly journals Temperature Field Evolution in Wood Samples During the Flame Spread Experiments

2014 ◽  
Vol 9 (1) ◽  
pp. 16-24
Author(s):  
Lucie Hasalová ◽  
Petr Vaněk ◽  
Milan Jahoda
Keyword(s):  
Cross Section ◽  
Flame Spread ◽  
Rectangular Cross Section ◽  
Small Scale ◽  
Temperature Profiles ◽  
Internal Temperature ◽  
Upward Flame Spread ◽  
Horizontal Orientation ◽  
Square Prism ◽  
Computational Fluid Dynamics Cfd

Abstract Vertical, horizontal and 45° upward flame spread experiments over the small scale beech and pine wood samples were performed. Wood samples were of two geometries - square cross section prisms (15 x 15 mm) and a thin rectangular cross section prisms (5 x 40 mm) - and of three different lengths - 10, 15 and 30 cm. Samples were ignited by a heptane source fire extinguished immediately when the wood samples ignited. During the flame spread an internal temperature profiles along the centreline of the samples were measured by a set of thermocouples. Flame spread was observed in all sample positions except the horizontal orientation of the beech and pine square prism samples. Experimental data will serve for a validation of the pyrolysis models in the Computational Fluid Dynamics (CFD) flame spread models.

scholarly journals Calculating propulsive and restoring electromagnetic forces between massive circular coils of rectangular cross section with inclined axes in air

2021 ◽  
Vol 2 (1) ◽  
pp. 110-121
Author(s):  
Slobodan Babic ◽  
Cevdet Akyel ◽  
Levent Erdogan
Keyword(s):  
Cross Section ◽  
Rectangular Cross Section ◽  
Small Scale ◽  
Published Data ◽  
Electromagnetic Forces ◽  
Restoring Forces ◽  
Good Agreement

In this paper we give the new formulas for calculating the propulsive and the restoring electromagnetic forces between the loops in air whose centers are in the different axes. These new formulas are used to calculate the propulsive and the restoring forces between two inclined massive coils of rectangular cross section whose centers are in the different axes. The filament method is used. Results obtained by the presented approach are in remarkably good agreement with already published data. Electromagnetic forces can be used for various applications, it is very versatile; there are a plethora of ways to utilize electromagnetic forces and energy, from small scale uses e.g., microchips to larger scale and lifesaving uses e.g., radiotherapy.

Front Condition for Gravity Currents in Channels of Nonrectangular Symmetric Cross-Section Shapes

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
B. M. Marino ◽  
L. P. Thomas
Keyword(s):  
Froude Number ◽  
Cross Section ◽  
Laboratory Experiments ◽  
Rectangular Cross Section ◽  
Theoretical Models ◽  
Gravity Currents ◽  
Cross Section Shape ◽  
Section Shape ◽  
Front Condition ◽  
Upper Boundary

We study the variation of the Froude number at the front of gravity currents developed in uniform channels whose cross-section shape depends on a parameter usually used in many numerical and theoretical models. The thickness and front velocity of the dense currents running on the bottom are greater for all the cases studied, resulting in a Froude number greater than that corresponding to the rectangular cross-section shape. The light currents developing along the upper boundary show the opposite trend. It is found that the results are not related to the depth and width of the channel. The relationships obtained agree with the results of laboratory experiments in which open and closed channels of different cross-section shapes are used.

Confinement of Masonry Columns with PBO and Basalt FRCM Composites

2019 ◽  
Vol 817 ◽  
pp. 392-397 ◽  
Author(s):  
Luciano Ombres ◽  
Antonio Iorfida ◽  
Salvatore Verre
Keyword(s):  
Composite Materials ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Structural Response ◽  
Small Scale ◽  
Masonry Structures ◽  
Control Specimen ◽  
Fiber Reinforced ◽  
Cementitious Matrix ◽  
New Generation

A new generation of composite materials in the form of Fiber Reinforced Cementitious Matrix (FRCM) was recently used to strengthen the masonry structures. Six small scale masonry columns were tested under monotonic concentric load until collapse; three columns were confined with PBO (short of polyparafenilenbenzobisoxazole)-FRCM jackets, two with basalt–FRCM jackets while an unconfined column was used as a control specimen. The masonry columns investigated have a rectangular cross section 250x250 mm among the overall length equal to 770 mm, and the corners were rounded to a radius of 20 mm. The analysis was conducted varying the confinement ratio i.e. the number of fabric layers for each FRCM system. Obtained results allow evidencing the effectiveness of the confinement and the effect n-layer on the structural response of the masonry columns.

Analyzing the architecture of point bar of meandering fluvial river using ground penetration radar: A case study from Hulun Lake Depression, China

2019 ◽  
Vol 7 (2) ◽  
pp. T437-T454 ◽  
Author(s):  
Dali Yue ◽  
Wei Li ◽  
Wurong Wang ◽  
Guangyi Hu ◽  
Bingbei Shen ◽  
...  
Keyword(s):  
Qualitative Description ◽  
Small Scale ◽  
Limited Information ◽  
Depositional Facies ◽  
Point Bar ◽  
Architecture Model ◽  
Reflection Seismic ◽  
Abandoned Channel ◽  
Point Bars ◽  
Hydrocarbon Distribution

The point bar is one of the most important reservoirs in a meandering depositional system, and accurately building a 3D architecture model for point bars is crucial to predict hydrocarbon distribution within the reservoir. Unfortunately, we can only obtain a qualitative description about the internal architecture of the point bar due to the limited information or the low resolution of available data (such as reflection seismic data). To build a 3D prototype point bar reservoir model, we analyze the architecture of point bars by integrating high-resolution ground penetrating radar (GPR) data and modern deposition. We found that our GPR data have five main reflection patterns (GPR facies), and GPR facies can be used to relate with architectural elements (the depositional facies and geobodies within depositional facies). The concave-down GPR facies is usually related to the abandoned channel. The continuous, subhorizontal, subparallel GPR facies is commonly related with lateral-accretion sand bodies within the point bar. The multiple stacked small-scale, discontinuous reflections GPR facies is interpreted to be shale drapes within the point bar. We further analyzed the geometry parameters of the identified channels. We found that the nonsymmetric [Formula: see text] of abandoned channel near the channel axis is related to the ratio between the curvature of channel radius [Formula: see text] and channel width [Formula: see text] ([Formula: see text]). Finally, we built two 3D channel reservoir models and our models could provide useful guidance for the architecture analysis of buried meandering fluvial reservoirs.

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