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Analysis of factors affecting destabilization of a viscous liquid flow in channels

Mamedov Asiman, Hnativ Roman, Yakhno Oleg, Murashchenko Alena

International Journal of Applied Mechanics and Engineering

2023

Vol. 28, no. 3

86--100

An analysis of the influence of inertia forces and ponderomotive forces on the destabilization of the flow of viscous fluids in the hydrodynamic initial section is given. Cases of flow of viscous, anomalously viscous and electrically conductive liquids are considered; the degree of influence of mass forces on the destabilization of the flow is estimated. As applied to the flow in the hydrodynamic initial section, the degree of influence of inertia forces from convective acceleration and forces with a magnetic nature can be different. Inertia forces stimulate the accelerated movement of the fluid, and in the case of forces with a magnetic nature, ponderomotive forces contribute to deceleration, which is confirmed by the results of studies of the velocity field. Recommendations are given for calculating the length of the hydrodynamic initial section in the presence of mass forces with different nature.

Visualization of River Water Flow in Hydrodynamically Active Areas under Different Flow Regimes

Snitynskyi Volodymyr, Khirivskyi Petro, Hnativ Ihor, Yakhno Oleg, Machuga Oleg, Hnativ Roman

Journal of Ecological Engineering

2021

Vol. 22, nr 9

129--135

It was established that in the territory of the Stryi river basin, the natural landscapes are maximally preserved in comparison with other regions of Western Ukraine, but under modern conditions an increase of negative anthropogenic impact on the quality of natural waters is observed. The hydrodynamic barriers or hydrodynamically active areas (HAA) of mountain rivers, characterized by a significant oxygen saturation of the water flow, which activates the processes of biochemical and biological self-purification of surface waters, are important for the efficiency of self-purification processes. In order to verify the results of theoretical and field research, an existing experimental setup was designed and improved. It provided the conditions for modeling the flow of mountain rivers in accordance with the laws of similarity theory and the principles of hydrodynamic modeling. On the basis of the results of field observations in the foothills of rivers, as well as regulatory and design documentation, the limits of the main operating factors were determined, namely the Freud number, flow depth and flow rate, which are decisive in studying the impact of HAA on flow self-cleaning processes. By changing the length of the tray section, the gullies and the waterfall niche of the real hydrodynamically active section were simulated, on which field experiments on the Tyshivnytsia River were conducted. In the studies, measurements were performed at different flow regimes, which simulated different hydrological parameters. In order to analyze the impact of HAA on self-cleaning processes, the flow was visualized using photography. The change in the structure of a stream of natural waters at passage of HAA was established. The high oxygen saturation of the river waters of the Stryi river basin is caused by the influence of HAA, which contribute to the purification of polluted waters from biological pollutants and other man-made pollutants and form the high quality of water resources in the region. A method of modeling and visualization of mountain rivers in the laboratory was developed.