Stretches of fluid materials for Stokes flow in circular cavity

Stretching for fluid materials slowly flowing within a circular cavity is investigated in the present study. Two belts, which are performed in periodic rotations on the boundary, are used to drive the flow motions. It is shown that the stretching values of fluid filaments are very sensitive to the boundary conditions for which different periods and different angle-phase-shifts are used. Flows generated by the rotations with longer periods and/or Rows generated by the two belts rotating out-phase will create greater stretchings, and possibly better stirrings. Furthermore, under these situations the stretching values associated to fluid filaments are much uniformly distributed.