In this paper, we investigate experimentally the concept of energy harvesting from galloping oscillations with a focus on wake and turbulence effects. The harvester is composed of a unimorph piezoelectric cantilever beam with a square cross-section tip mass. In one case, the harvester is placed in the wake of another galloping harvester with the objective of determining the wake effects on the response of the harvester. In the second case, meshes were placed upstream of the harvester with the objective of investigating the effects of upstream turbulence on the response of the harvester. The results show that both wake effects and upstream turbulence significantly affect the response of the harvester. Depending on the spacing between the two squares and the opening size of the mesh, wake and upstream turbulence can positively enhance the level of the harvested power.Converting aeroelastic vibrations into electricity has been proposed for energy harvesters design that can be used to operate self-powered small electronic devices or to take the place of small batteries, which have a finite-life span or require expensive and hard maintenance. Depending on the operating wind speed, piezoaeroelastic energy harvesters can be designed and deployed in different locations, such as structure's surface, ventilation outlets, rivers, etc., to power sensors or actuators. Several investigations have focused on harvesting energy from flow-induced vibrations, such as vortex-induced vibrations of circular cylinders, 1-4 flutter of airfoil sections, 5-13 wake galloping, 14,15 and galloping of prismatic structures. [15][16][17][18][19][20][21][22] The transverse galloping phenomenon has shown a promise for effective energy harvesting. For instance Sirohi and Mahadik 16 reported that at a wind speed of 11.6 mph (1 mph = 0.447 m/s) most of the commercial wireless sensors can be supplied by their proposed piezoaeroelastic energy harvester. To design enhanced galloping-based piezoaeroelastic energy harvesters, Abdelkefi et al. 17-21 studied the effects of the cross-section geometry, Reynolds number, electrical load resistance, ambient temperature on the onset speed of galloping, and the harvested power's lever. Yang et al. 22 experimentally investigated the effects of the cross-section geometry on the performance of galloping-based piezoelectric energy harvesters.In all of the above studies, the harvesters were subjected to uniform wind speed. In this work, a) Corresponding author.

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The processes of long-range granitic magma transfer from mid-and lower crustal anatectic zones to upper crustal pluton emplacement sites remain controversial in the literature. This is partly because feeder networks that could have accommodated this large-scale magma transport remain elusive in the field. Existing granite ascent models are based largely on numerical and theoretical studies that seek to demonstrate the viability of fracture-controlled magma transport through dykes or self-propagating hydrofractures. In most cases, the models present very little supporting field evidence, such as sufficiently voluminous near-or within-source magma accumulations, to support their basic premises. We document large (deca-to hectometre-scale), steeply dipping and largely homogeneous granite lenses in suprasolidus (~5 kbar,~750°C) mid-crustal rocks in the Damara Belt in Namibia. The lenses are surrounded by and connected to shallowly dipping networks of stromatic leucogranites in the well-layered gneisses of the deeply incised Husab Gorge. The outcrops define a four-stage process from (i) the initial formation and growth of large, subvertical magma-filled lenses as extension fractures developed at high angles to the subhorizontal regional extension in relatively competent wallrock layers. This stage is followed by (ii) the simultaneous lateral inflation and (iii) subcritical vertical growth of the lenses to a critical length that (iv) promotes fracture destabilization, buoyancy-driven upward fracture mobilization and, consequently, vertical magma transport. These field observations are compared with existing numerical models and are used to constrain, by referring to the dimensions of the largest preserved inflated leucogranite lens, an estimate of the minimum fracture length (~100 m) and volume (~2.4 9 10 5 m 3 ) required to initiate buoyancy-driven brittle fracture propagation in this particular mid-crustal section. The critical values and field relationships compare favourably with theoretical models of magma ascent along vertical self-propagating hydrofractures which close at their tails during propagation. This process leaves behind subtle wake-like structures and thin leucogranite trails that mark the path of magma ascent. Reutilization of such conduits by repeated inflation and drainage is consistent with the episodic accumulation and removal of magma from the mid-crust and is reflected in the sheeted nature of many upper crustal granitoid plutons.

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