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Dynamics of particles in stationary and oscillating flows

The motion of small bodies in a hydrodynamic flow is a classical problem of fluid dynamics. Since 1980s-1990s the corresponding studies have been largely intensified due to the new applications, such as tracing impurities in the ocean and new biomedical applications of ultrasound. This presentation discusses some of these results.�� First, a rather complex, possibly chaotic dynamics of a particle in circular and cellular fluid flows is considered for an ideal and viscous fluid, including the effect of the inertial Basset force. Then we specifically consider the action of oscillating flows which creates a translational motion of particles and bubbles caused by a period-averaged “radiation force.”�� The latter phenomenon is of special interest due to the new biomedical applications of ultrasound such as mixing and steering of components in microfluidics, measurements of bacterial content in blood and food, and many others. Here we��present the theory of the averaged motion of particles and bubbles in the acoustic field. Then some experimental results and existing applications are outlined.