Experimental evaluation of the drag force and drag torque acting on a rotating spherical particle moving in fluid

The paper describes results of experiments with rotating spherical particles moving in water. Rubber spherical balls with the density close to that of water were speeded up in a special inclined chute that ensured the required particle rotational and translational velocity in the given plane. A standard video system was used to capture particle trajectory and the evaluation was focused on the effects of two dimensionless parameters of the particle motion, Reynolds number and rotational Reynolds number. The values of the drag force and drag torque coefficients were determined from the experimental data and compared with the results of the numerical simulation of the particle motion. Relationships describing the above mentioned quantities, taking into account the mutual influence of the translational and the rotational particle movements and convenient for numerical models were found.