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Inspired by the natural motion of insects, fish, and other animals, flapping airfoils have gained significant importance due to their applications in fields such as ship propulsion, micro aerial vehicles, and autonomous underwater vehicles.…
The understanding of interaction effects between marine energy converters represents the next step in the research process that should eventually lead to the deployment of such devices. Although some a priori considerations have been…
The wake of a flexible foil undergoing pitching oscillations in a low-speed hydrodynamic tunnel is used to examine the effect of chord-wise foil flexibility in the dynamical features of flapping-based propulsion. We compare the regime…
The angle of repose for the flow of granular materials in a half-filled rotating drum is studied by means of experiments and computer simulations. Particles of different material properties are used to investigate the effects of the end…
For the dynamic analysis of floating offshore wind turbines (FOWTs) in realistic operating environment, this paper develops a coupled aero-hydro-mooring-servo model applicable to turbulent wind and irregular sea states with high…
We experimentally study the influence of wall roughness on bubble drag reduction in turbulent Taylor-Couette flow, i.e.\ the flow between two concentric, independently rotating cylinders. We measure the drag in the system for the cases with…
Photophoretic levitation is a propulsion mechanism in which lightweight objects can be lifted and controlled through their interactions with light. Since photophoretic forces on macroscopic objects are usually maximized at low pressures,…
Aerial manipulators are increasingly used in contact-based industrial applications, where tasks like drilling and pushing require platforms to exert significant forces in multiple directions. To enhance force generation capabilities,…
This research investigates the three-dimensional effects of flow around a pair of flapping wings undergoing clap-and-fling interactions through harmonic in-plane motions combining pitching, heaving, and deviation. Both wings mirror each…
As platform size is reduced, the flight of aerial robots becomes increasingly energetically expensive. Limitations on payload and endurance of these small robots have prompted researchers to explore the use of bimodal aerial-surface…
Gridded ion thrusters are tested in ground vacuum chambers to verify their performance when deployed in space. However, the presence of high background pressure and conductive walls in the chamber leads to facility effects that increase…
Wake redirection is a promising approach designed to mitigate turbine-wake interactions which have a negative impact on the performance and lifetime of wind farms. It has recently been found that substantial power gains can be obtained by…
We perform direct numerical simulations of flows over finite-aspect-ratio rotating circular cylinders at a Reynolds number of 150 over a range of aspect ratios ($AR=2-12$) and rotation rates ($\alpha=0-5$), aiming at revealing the free-end…
The torsion loading of a coupled cylinder, comprising distinct upper and lower cylindrical sections potentially made of different materials, is considered. The bottom of the cylinder is fixed in place, and induces the cylinder vibration.…
Rotational inertia is stabilizing the frequency of electric power systems against small and large disturbances, but it is also the cause for oscillations between generators. As more and more conventional generators are replaced by renewable…
This paper numerically investigates the influence of a fixed downstream control cylinder on the flow-induced vibration of an elastically-supported primary cylinder. These two cylinders are situated in a tandem arrangement with small…
In this work, we describe the impact of aspect ratio (AR) on the performance of optimally phased, identical flapping flippers in a tandem configuration. Three-dimensional simulations are performed for seven sets of single and tandem finite…
Slip-boundary effects on the polar liquid film motor (PLFM) -- a novel micro-fluidic device with important implications for advancing knowledge on liquid micro-film's structure, dynamics, modeling and technology -- are studied. We develop a…
In this work, we have performed numerical simulations of the flapping motion of a rectangular wing in a three-dimensional flow field using the discrete vortex method (DVM). The DVM method is computationally more convenient because it does…
We study numerically the two-dimensional flow past a circular cylinder as a prototypical transitional flow, and investigate the influence of a generic slip boundary condition on the wake dynamics. We show that slip significantly delays the…