Cooperative action of motile micro-pillars: from micro-scale fluid-structure interaction to effictive near-wall flow control

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The proposed project is a detailed study of flow in arrays of micro-pillars inspired from our collaboration with the research group of Prof. Spatz, Univ. Stuttgart. The previous study focused on the behavior of flexible filaments tethered by micro-pillars close to the wall for turbulent drag reduction. In the renewal application, we extend the developed technique to motile micro-pillar arrays, where the motility of the flexible pillars is used to generate streaming motion near the wall either by passive or active excitation of the micro-pillars. A specific arrangement of the micro-pillars on the wall leads to a cooperative flow interaction at microscale yielding a highly effective flow control. In transitional boundary layer flow the nearwall fluctuations themselves are used to stimulate the micro-pillar bundles and the so induced local flow vectoring is useful for flow control. In the active case, magnetically actuation of the micro-pillars can be used for effective near wall flow control either by shape-depending flow vectoring or traveling wave mechanism. The conditions of optimum shape and arrangement of the micro-pillar arrays for local flow control are developed and applied in experimental devices.