A slip-transpiration-vortex model for riblets past the viscous regime

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2025年3月24日

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Alessandro Bottaro,
Giulia Innocenti,
Essam Nabil Ahmed

摘要

A new boundary condition at a plane, fictitious wall, meant to simulate the presence of small-scale streamwise-aligned riblets is outlined and tested. The need for an approach which extends beyond the viscous regime stems from the high cost of numerically resolving microscopic flow details within micro-ribs, and from the desire to rapidly optimize a variety of wall textures. A multiscale homogenization technique which accounts for advection is coupled to a synthetic vortex model which mimics the transverse flow in the near-wall region. The proposed wall model captures the non-monotonic behavior of the skin-friction drag over ribleted surfaces with the increase in $\ell ^+$ $ℓ^{+}$ (the pitch distance measured in viscous units), including the performance degradation and the eventual drag increase beyond some $\ell ^+$ $ℓ^{+}$ threshold.