Abstract
Motivated by the emerging applications of liquid-infused surfaces (LIS), we study the drag reduction and robustness of transverse flows over two-dimensional microcavities partially filled with an oily lubricant. Using separate simulations at different scales, characteristic contact line velocities at the fluid-solid intersection are first extracted from nanoscale phase field simulations and then applied to micronscale two-phase flows, thus introducing a multiscale numerical framework to model the interface displacement and deformation within the cavities. As we explore the various effects of the lubricant-to-outer-fluid viscosity ratio , the capillary number Ca, the static contact angle , and the filling fraction of the cavity , we find that the effective slip is most sensitive to the parameter . The effects of and are generally intertwined but weakened if . Moreover, for an initial filling fraction , our results show that the effective slip is nearly independent of the capillary number when it is small. Further increasing Ca to about , we identify a possible failure mode, associated with lubricants draining from the LIS, for . Very viscous lubricants (e.g., ), however, are immune to such failure due to their generally larger contact line velocity.
3 More- Received 28 September 2017
DOI:https://doi.org/10.1103/PhysRevFluids.3.054201
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