Inclination Angle Of Bottom Research Articles

Effects of flow condition and chute geometry on the shockwaves formed on chute spillway

Abstract Shock waves have undesirable effects, such as excessive dynamic pressure on spillway walls and the extension of flow beyond spillway conduits. To eliminate these detrimental impacts, designers have attempted to detect the characteristics of these waves. Flow interaction with chute piers generates triple waves in the middle walls and sidewalls of spillway conduits. The present study quantitatively investigated the characteristics of these waves with respect to variations in the bottom inclination angle (θ), wall contraction (φ), and Fr numbers (). The results indicated that with the increment of θ, , (φ, ), and (θ, ), the height () and distance () of the first wave increased, which can be helpful for flow aeration. Furthermore, owing to a boost in θ, , (φ, ), and (θ, ), the height of the second wave was decreased. Therefore, the amount of dynamic pressure on the spillway walls was reduced. Moreover, the distance of decreased with a rise in θ, φ and increased with the increment of and (φ, ). As for , raising φ and (φ, ) elevated the height of this wave and declined its distance. An increase in the height of boosted the flow turbulence and aeration.

Mathematical Modeling the Dynamics of the Bottom Sediments Granulometric Composition in the Balaklava Bay Affected by the Wind Waves

Purpose. Based on the mathematical modeling methods, influence of the wind waves on redistribution of the sand fractions in the semi-closed estuary-type water area is estimated using the Balaklava Bay as an example. Methods and Results. A two-dimensional version of the XBeach model with a constant grid spacing 10 m was used. The characteristics of wind waves were preset using the JONSWAP spectrum. The calculations were carried out for a storm event lasting about 12 hours once a year. The in-situ data on the particle size distribution in the bottom sediments resulted from the monitoring observations in the Balaklava Bay region was used in the numerical experiments. Conclusions. The results of modeling showed that the basic determining factors regulating the sediments movement were the depth and the bottom slope. It is noted that changing of the bottom inclination angle between the isobaths 6–7 and 7–8 m leads to deposition of the large and medium fractions, and in the area between the isobaths 9–10 and 10–12 m – to accumulation of fine sand. It was revealed that in the Balaklava Bay water area, the main redistribution of sand material caused by the storm waves took place within the southern basin, as well as at the bay exit in the coastal zone of the Megalo-Yalo Gulf. This is primarily determined by the features of the Balaklava Bay coast orography, namely, the knee-shaped narrowness separating the northern and southern basins. Nevertheless, in the isolated northern part of the Balaklava Bay being affected by the storm waves, insignificant dynamics of sand material was observed. The fractions of bottom sediments are redistributed from the western coast to the central part of the basin and to the eastern coast of the bay.

Matematicheskoye modelirovaniye dinamiki granulometricheskogo sostava donnykh otlozheniy Balaklavskoy bukhty pod vozdeystviyem shtormovogo volneniya

Purpose. Based on the mathematical modeling methods, influence of the wind waves on redistribution of the sand fractions in the semi-closed estuary-type water area is estimated using the Balaklava Bay as an example. Methods and Results. A two-dimensional version of the XBeach model with a constant grid spacing 10 m was used. The characteristics of wind waves were preset using the JONSWAP spectrum implying fixed height, wave period and various combinations of the wave direction. The calculations were carried out for a storm event lasting about 12 hours once a year. The in-situ data on the particle size distribution in the bottom sediments resulted from the monitoring observations performed by the Marine Hydrophysical Institute, Russian Academy of Sciences, in the Balaklava Bay region was used in the numerical experiments. Conclusions. The results of modeling showed that the basic determining factors regulating the sediments movement were the depth and the bottom slope. It is noted that changing of the bottom inclination angle between the isobaths 6–7 and 7–8 m leads to deposition of the large and medium fractions, and in the area between the isobaths 9–10 and 10–12 m – to accumulation of fine sand. It was revealed that in the Balaklava Bay water area, the main redistribution of sand material caused by the storm waves took place within the southern basin, as well as at the bay exit in the coastal zone of the Megalo-Yalo Bay. This is primarily determined by the features of the Balaklava Bay coast orography, namely, the knee-shaped narrowness separating the northern and southern basins. Nevertheless, in the isolated northern part of the Balaklava Bay being affected by the storm waves, insignificant dynamics of sand material was observed. The fractions of bottom sediments are redistributed from the western coast to the central part of the basin and to the eastern coast of the bay.

Discharge of a silo through a lateral orifice: Role of the bottom inclination versus friction.

In this work we propose to identify the relative role of the inclination of gravitational acceleration and friction on the discharge flow rate of a granular media from a rectangular silo by varying the silo geometry thanks to an inclined bottom which ends up at a lateral outlet. The study is motivated by a nuclear safety problem: a fuel rod (modeled by an elongated silo) accidentally releases fuel fragments (modeled by grains). We performed experiments where we independently measured the mass flow rate and the velocity profiles, together with discrete particle simulations and continuum simulations with a frictional rheology described by a μ(I) constitutive law and taking into account the wall friction. We study monolayer flows and three-dimensional flows, and we propose an analytical model that predicts the discharge flow rate of particles from a rectangular silo with an inclined bottom according to its outlet aspect ratio and the bottom inclination angle.

Numerical Optimization Research on Rear Characteristic Angles Based on MIRA Model for Aerodynamic Drag Reduction

The rear characteristic angles of the passenger car in this study were defined as the inclination angle of rear window and the bottom inclination angle of aft based on the MIRA model. The numerical optimization method was used to analyze the influence of combined variation of two angles on the external flow field and the CD of the passenger car, in which we combined genetic algorithm with the CFD simulation to reduce aerodynamic drag by seeking the relatively optimal combination of two parameters above. The study reveals that when the combination of the inclination angle of rear window and bottom inclination angle of aft is 25oand 0.067o, the total pressure and streamline distribution in the flow fields of the MIRA model are improved greatly and the CD is reduced compared with the worst combination. This conclusion will have profound guiding significance in the aerodynamic design of the rear styling and shape of a car.

Integrated ef fective emissivity computation for non-isothermal non-axisymmetric cavities

Non-axisymmetric cavities are widely used as standard blackbody sources for radiation thermometry. The integrated effective emissivity is central to the blackbody design. Integrated effective emissivities are numerically calculated for non-isothermal, non-axisymmetric cavities. The average relative deviation is 0.087% when compared with Monte-Carlo results, indicating that this method can accurately calculate the integrated effective emissivities for non-isothermal, non-axisymmetric cavities. The effects of the wavelength, temperature uniformity, and bottom inclination angle are then analyzed.

Characteristics of Hydraulic Shock Waves in an Inclined Chute Contraction - Experiments

AbstractThis paper presents the experimental results of the characteristics of hydraulic shock waves in an inclined chute contraction with consideration of the effects of sidewall deflection angle φ, bottom inclination angle θ and approach Froude number Fr0. Seventeen runs of laboratory experiments were conducted in the range of 27.45° ≤φ≤ 40.17°, 6.22°≤ θ ≤ 25.38° and 1.04 ≤ Fr0 ≤ 3.51. Based on the experimental data, three empirical dimensionless relations for the shock angle, maximum shockwave height, and corresponding position of maximum shockwave were obtained by regression analyses, respectively. These empirical relations would be useful for hydraulic engineers in designing chute contraction structures.

Characteristics of Hydraulic Shock Waves in an Inclined Chute Contraction - Experiments

AbstractThis paper presents the experimental results of the characteristics of hydraulic shock waves in an inclined chute contraction with consideration of the effects of sidewall deflection angle φ, bottom inclination angle θ and approach Froude number Fr0. Seventeen runs of laboratory experiments were conducted in the range of 27.45° ≤φ ≤ 40.17°, 6.22° ≤ θ ≤ 25.38° and 1.04 ≤ Fr0 ≤ 3.51. Based on the experimental data, three empirical dimensionless relations for the shock angle, maximum shockwave height, and corresponding position of maximum shockwave were obtained by regression analyses, respectively. These empirical relations would be useful for hydraulic engineers in designing chute contraction structures.

Effective emissivity of a cylindrical cavity with an inclined bottom: I. Isothermal cavity

The Monte Carlo method is applied to the computation of the effective emissivity of a specular–diffuse isothermal blackbody cavity shaped by a cylindrical generatrix, a flat inclined bottom and a flat diaphragm. The dependences of the normal effective emissivity on the bottom inclination angle are studied for different cavity depths and various values of the diffuse component of the cavity wall reflectance. The distributions of the local normal effective emissivity over the cavity aperture and the dependences of the integrated effective emissivity on the distance between the aperture and the radiation detector are computed. The choice of optimal geometrical parameters for improving the radiometric performance of artificial blackbodies is discussed.