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Collision of a rotating spherical particle with flat wall in liquid
Lukerchenko, Nikolay ; Kvurt, Y. ; Chára, Zdeněk ; Vlasák, Pavel
The collision of the rotating spherical particle with a flat wall in liquid was studied experimentally. The glass and steel beads rotating in water and silicon oil were used. A high-speed video system recorded the bead motion before and after the collision. It was shown that the restitution coefficient depends not only on the Stokes number but also on the particle angular velocity; the restitution coefficient decreases with increasing of the rotational Reynolds number and decreasing of the Stokes number. These results can be useful in modelling of the two-phase flows near solid boundaries.
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Motion of rotating spherical particles touching a wall
Chára, Zdeněk ; Vlasák, Pavel ; Keita, Ibrahima
The paper deals with an analysis of motion of rotating spherical particle in calm water, when the particle is in contact with a smooth, horizontal wall. The motion was visualized by a fast digital camera at 1000 frames/second. Based on software analysis the particle trajectories as well as rotational velocities were determined. Values of vertical, horizontal and rotational velocities were used as input parameters for numerical model and the results are compared with experimental data. Experiments were performed with glass particle of diameter 25 mm, initial values of rotational speeds varied from 500 to 3000 revolution per minute.
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Experimentální výzkum Magnusovy síly působící na hladkou kouli při vysokých Reynoldsových číslech
Kharlamov, Alexander ; Chára, Zdeněk ; Vlasák, Pavel
Článek popisuje výsledky pokusů s rotující hladkou kulovou částicí při kvazi-stabilním pohybu v klidné vodě. Pohyb částice byl zaznamenán digitální videokamerou a kinematické parametry pohybu částice numericky analyzovány. Bezrozměrný součinitel Magnusovy síly, Reynoldsovo číslo a spin parametr Γ (poměr obvodové rychlosti rotující částice a její translační rychlosti) byly vyhodnoceny z časových řad souřadnic a úhlů rotace částice. Magnusova síla byla určena v závislosti na Reynoldsově čísle a spin parametru pro oblast 3000 < Re < 42000 a 0,1 < Γ <7. Výsledky byly porovnány s literárními údaji a data byly aproximovány jednoduchou funkcí platnou pro oblast 0,5 < Re < 140000 a 0,1 < Γ <10.
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Magnus and Drag Forces Acting on Golf Ball
Kharlamov, Alexander ; Chára, Zdeněk ; Vlasák, Pavel
The paper describes the results of experiments with a rotating golf ball moving quasi-steadily in calm water. The motion of the ball was recorded on a digital video camera. The Cartesian coordinates and the angle of rotation of the ball were determined from the records of motion. The dimensionless drag force coefficient, Magnus force coefficient and translational and rotational Reynolds numbers were calculated from the time series of the ball coordinates and the angle of rotation for each recorded frame. The calculated data were averaged over rectangular cells on experimental domain on the plane of translational and rotational Reynolds numbers, i.e. 1.2 104 < Re < 1.6 104 and 3.8 103 < Reω < 2.7 104. The coefficients were presented in tabulated form.
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