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Kinematic rotary control is here proposed conceptually to enhance energy harvesting from Transverse Galloping. The effect of actively orientating the galloping body with respect to the incident flow, by imposing externally a rotation of the body proportional to the motion-induced angle of attack, is studied. To this end, a theoretical model is developed and analyzed, and numerical computations employing the Lattice Boltzmann Method are carried out. Good agreement is found between theoretical model predictions and numerical simulations results. It is found that it is possible to increase significantly the efficiency of energy harvesting with respect to the case without active rotation, which opens the path to consider this idea in practical realizations.

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Keywords:An experimental and numerical study is presented that focuses on the flow topology in finned heat sinks with tip Heat sink clearances. As it is well known, the use of tip clearances has, normally, a global beneficial effect. Typically, heat Tip clearance transfer may degrade (a negative effect) by a somewhat small percentage while pressure drop may decrease (a Heat transfer versus pressure drop positive effect) by a substantial amount. In this context, the important question from an R&D standpoint is to understand the flow topology so that the actual design of the tip clearance optimizes the balance between heat transfer and pressure drop. In this study, a 3D numerical method is validated, first, comparing with the Particle Image Velocimetry based experimental results obtained in the actual setup in isothermal conditions. Then, the flow solver thus validated is used in a series of thermal cases in which both the tip clearance height and Reynolds number are varied so as to clarify the flow topology. In particular, it has been found that the behavior of both heat transfer and pressure drop cannot be explained in view, only, of flow development and thermal development aspects. This is so because the Nusselt versus Graetz curves that have been generated do not collapse into a single fit; instead, they collapse into several families that are governed by the tip clearance parameter. Distinct heat transfer rates have been observed for the different fin walls. The transfer rate of the side walls is nearly three times larger than that of the bottom walls, and this suggests the optimum place to locate the heat sources in a practical engineering application. Nomenclature list Latin symbolsA w C Cp cs

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