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

拟议的项目是一项关于微柱阵列中流动的详细研究，灵感来自于我们与大学Spatz教授的研究小组的合作。斯图加特。前人的研究主要集中在靠近壁面的微柱上的柔性纤维的湍流减阻行为。在更新应用中，我们将所开发的技术扩展到可移动的微柱阵列，其中利用柔性柱的运动性通过对微柱的被动或主动激励来产生靠近壁面的流动运动。壁面上微柱的特定布置导致了微观尺度上的协同流动相互作用，从而产生了高效的流动控制。在过渡边界层流动中，近壁波动本身被用来激励微柱束，由此产生的局部流动矢量对流动控制是有用的。在有源情况下，微柱的磁致动可以通过形状相关的流动矢量或行波机制来实现有效的近壁流动控制。建立了用于局部流动控制的微柱阵列的最佳形状和排列条件，并在实验装置上进行了应用。

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.