Effective slip in pressure-driven flow past superhydrophobic stripesстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
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Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:A super-hydrophobic array of grooves containing trapped gas (stripes) has the
potential to greatly reduce drag and enhance mixing phenomena in microfluidic
devices. Recent work has focused on idealized cases of stick-perfect slip stripes.
Here, we analyse the experimentally more relevant situation of a pressure-driven flow
past striped slip-stick surfaces with arbitrary local slip at the gas sectors. We derive
approximate formulas for maximal (longitudinal) and minimal (transverse) directional
effective slip lengths that are in a good agreement with the exact numerical solution
for any surface slip fraction. By representing eigenvalues of the slip length tensor, we
obtain the effective slip for any orientation of stripes with respect to the mean flow.
Our results imply that flow past stripes is controlled by the ratio of the local slip
length to texture size. In the case of a large (compared to the texture period) slip at the
gas areas, surface anisotropy leads to a tensorial effective slip, by attaining the values
predicted earlier for a perfect local slip. Both effective slip lengths and anisotropy of
the flow decrease when local slip becomes of the order of texture period. In the case
of a small slip, we predict simple surface-averaged isotropic flows (independent of
orientation).