Dynamic of a Microsphere inside an Spherical Cavity with Newtonian Fluid Subjected to Periodical Contractions

  • Castilla, Robert (Universitat Politecnica de Catalunya)

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The dynamics of a microsphere submerged in an spherical cavity is numerically analyzed. The cavity, filled with a newtonian fluid, is subjected to periodical contractions in its surface that create flows that affects to the microsphere dynamics. The space distributions of force and drag resistance are estimated by unsteady three-dimensional computational simulations with dynamic mesh. These distributions are functions of sphere size and position, and they are fitted to mathematical models. Dynamic simulations are performed using these mathematical models to compute the trajectory of the microsphere under the action of thousands of position-dependent pushing–pulling forces. A dynamic simulation is performed with one-dimensional finite differences. It is shown that in the long term, ball tend to migrate to the center of the cavity, especially when it is small compared with the cavity size.