Discontinuous Meniscus Location in Tapered Capillaries Driven by Pressure Difference and Dielectrophoretic Forces

摘要

We calculate the meniscus location in tapered capillaries under the influenceof pressure difference and dielectrophoretic forces with and without gravity.We find that the meniscus location can be a discontinuous function of thepressure difference or the applied voltage and that the meniscus can ``jump''to one end or another of the capillary. Phase diagrams are given as a functionof the pressure and voltage, depending on the geometrical parameters of thesystem. We further consider a revision of the dielectric rise underdielectrophoretic force in wedge capillaries and in the case of electrowetting,where the dielectrophoretic force is a small perturbation. Finally, we alsofind discontinuous liquid--gas interface location in the case of liquidpenetration into closed volumes.