Untersuchungen zum Fallverhalten würfelförmiger Einzelkörper in Wasser

TL;DRAbstract

The underwater fall of cubes (as reference bodies for sharp edged quarry rock material) of different sizes and densities has . been examined. The experimental study has been carried out by using a shaft (diameter: 5 m) filled with water. Due to rotary motion (Magnus' effect), the trajectories of such cubes deviate from vertical lines. The direction of such deviation cannot be predicted, because the axis of rotation changes irregularly during the fall. The cubes reach their settling velocities very fast. The observed settling velocities are in accordance with the values obtained from the general quadratic law for resistance. The drag coefficient Cw is 0,8 - independent of the size and density of the cube - referred to the maximum projection area. Since the effected projection area changes during a cube's fall, the instantaneous velocity of this object oscillates. The oscillation can sometimes be as large as 25 % of the calculated mean value.

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