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Coherent structures around submerged circular and square cylinders due to change of orientation angle in steady current over plane bed

Bauri Krishna Pada

Acta Geophysica

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2022

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Vol. 70, no 5

2223--2250

EN

The investigation of the bursting process and coherent structures around circular and square cylindrical structures for various angular alignments over a rigid plane bed are introduced. The coherent structures and shear stresses perform a substantial characteristic in bed particle entrainment and transport from the bed around these structures. Hence, bed shear stress, power spectra are determined from the measured velocity data, in addition, third-order correlation, turbulence intensity, and kinetic energy were investigated using quadrant analysis to explore the correlation between coherent structures and sediment movement. Turbulent coherent structures due to the variations of submergence depth, velocity, orientation angle of the square cylinder, and cylinder size are also investigated. Further, the measured velocity data using Acoustic Doppler Velocimeter were validated with numerical simulations using COMSOL Multiphysics 5.0 with k-ω turbulence closure model. Outcomes indicate that the wake zone length rises with the rise of submergence ratio for the square cylinder with different angular alignments than the circular and square cylindrical structures. Bed shear stress is higher for the square cylinder with different angular alignments than the circular cylinder. The wake vortex strength increases with angular alignment signifying excessive movement of bed sediments from the bed around the cylindrical structures. The interaction events predominate near the bed and middle height of the cylinder, whereas ejection and sweep events dominate far away from the bottom toward the top of the cylinders. The stress fraction is maximum for square cylinders with higher alignment angles.

2

Comparative Analysis of Effect of Wind Loads with Variation in Altitude and Angle of Inclination of Wind Direction on Solar Panels

Surendra Reddy P., Swapna K., Kiran Kumar G., Krishna Varma K. P. V.

Ecological Engineering & Environmental Technology

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2021

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Vol. 22, iss. 6

61--68

EN

Solar panels are used in wide range of applications like power generation, automobiles, electronic devices etc. They are trending devices which develop power from abundantly available solar energy. In spite of this advantage, they are affected by wind loads, which result in wind induced loading. Determining this is very essential because, the drag and lift forces applied on the solar panels due to the wind loads play a crucial role in the accomplishment of performance in the solar panels. In this work, an attempt was made to carry out a comparative analysis of the effect caused by the wind forces on different array sizes, altitudes, orientation of the solar panels at different wind speeds (5 m/s, 25 m/s) and at different inclination angles the wind (0°, 45°, 135° and 180°. The ultimate objective of this work was to analyze the effect caused by wind forces based on these combinations of the parameters. Different shapes of solar panels like rectangular and hexagonal shaped were analyzed for normal and optimized conditions. Moreover, wind load analysis was carried out for different altitudes like on the ground and on the roof top. The outcomes depict that the wind forces on front region of the conventional solar panels is higher when compared to the optimized solar panel.

3

Crossing axes of workpiece and tool at grinding of the circular trough with variable profile

Kalchenko V., Yeroshenko A., Boyko S.

Acta Mechanica et Automatica

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2018

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Vol. 12, no. 4

281--285

EN

In the article the method of grinding with crossed axes of the tool and the workpiece got further developed. The work discloses a method of processing details having an external surface with a profile in the form of an arc of a circle of variable radius (for example, rolls of pipe rolling mills). The particular three-dimensional geometric models of the processing, shaping and profiling of abrasive wheels have been developed. A method for controlling the grinding process, which ensures the removal of allowances along equidistant curves has been offered. The developed method of grinding provides a constant depth of cutting according to the coordinate of profile processing. This is achieved at the expense of the synchronous inclination of the wheel and its insertion by the size of the allowance. The diameter of grinding wheel affects on the maximum angle of orientation of the wheel has been proven. It has been shown that increasing the diameter of the abrasive wheel has led to a slight decrease in value orientation angle.

4

Changes in the states of polarization of random electromagnetic beams in atmospheric turbulence

Li J., Zhao K., Lai Y.

Optica Applicata

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2017

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Vol. 47, nr 1

51--62

EN

Taking the random electromagnetic cosh-Gaussian beam as a typical example of random electromagnetic beams, the analytical expressions for the cross-spectral density matrix element of random electromagnetic cosh-Gaussian beams propagating through non-Kolmogorov atmospheric turbulence are derived, and used to study the changes in the states of polarization (degree of polarization, orientation angle and degree of ellipticity) of random electromagnetic cosh-Gaussian beams in non-Kolmogorov atmospheric turbulence. It is shown that the states of polarization of random electromagnetic cosh-Gaussian beams in non-Kolmogorov atmospheric turbulence are different from those in free space. The degree of polarization decreases, and the orientation angle and degree of ellipticity increase with increasing structure constant. The on-axis degree of polarization and the degree of ellipticity appear to have an oscillatory behavior and the orientation angle has a rapid transition for the larger cosh-part parameter of random electromagnetic cosh-Gaussian beams in atmospheric turbulence.