Related papers: Rather than drafting, vortex capture dictates effi…
Flapping foils are widely studied as bioinspired propulsors, yet most investigations have focused on regular, sinusoidal kinematics. In realistic environments, however, irregular motions arise naturally due to environmental disturbances,…
Submerged flapping foils can convert wave energy directly into thrust, which could be potentially utilised for green marine propulsion. This study analyses the wave-induced flapping hydrofoil propulsion using an in-house developed, new…
Biological and artificial microswimmers often self-propel in external flows of vortical nature; relevant examples include algae in small-scale ocean eddies, spermatozoa in uterine peristaltic flows and bacteria in microfluidic devices. A…
Three-dimensional wake of an oscillating foil with combined heaving and pitching motion is numerically evaluated at a range of chord-based Strouhal number (0.32 \le Stc \le 0.56) and phase offset (90 deg \le \phi \le 70 deg) at Re = 8000.…
Fluid flows play a central role in scientific and technological development, and many of these flows are characterized by a dominant oscillation, such as the vortex shedding in the wake of nearly all transportation vehicles. The ability to…
We derive from first principles a three-dimensional theory of self-propelled particle swarming in a viscous fluid environment. Our model predicts emergent collective behavior that depends critically on fluid opacity, mechanism of…
We present results from model tests to investigate the effect of drafting in swimming, in particular for the lead swimmer. The drag for scaled-model passive swimmers was determined accurately at Froude numbers comparable to conditions for…
Biological flapping wing fliers operate efficiently and robustly in a wide range of flight conditions and are a great source of inspiration to engineers. The unsteady aerodynamics of flapping-wings are dominated by large-scale vortical…
This study examines the impact of in-phase schooling on the hydrodynamic efficiency during linear acceleration in a simplified model using two undulating NACA0012 hydrofoils arranged in phalanx formation as a minimal representation of a…
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…
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.…
We consider a swimmer consisting of a collinear assembly of three spheres connected by two slender rods. This swimmer can propel itself forward by varying the lengths of the rods in a way that is not invariant under time reversal. Although…
A compact object moving relative to surrounding gas accretes material and perturbs the density of gas in its vicinity. In the classical picture of Bondi-Hoyle-Lyttleton accretion, the perturbation takes the form of an overdense wake behind…
We combine a general formulation of microswimmmer equations of motion with a numerical bead-shell model to calculate the hydrodynamic interactions with the fluid, from which the swimming speed, power and efficiency are extracted. From this…
The near wake of a small-scale wind turbine is investigated using Particle Image Velocimetry (PIV) experiments at different tip speed ratios ($\lambda$). The wind turbine model had a nacelle and a tower mimicking real scale wind turbines.…
Airborne insects generate a leading edge vortex when they flap their wings. This coherent vortex is a low pressure region that enhances the lift of flapping wings compared to fixed wings. Insect wings are thin membranes strengthened by a…
This study examines the performance of two flapping flat-plate foils interacting with each other while generating thrust at a Reynolds number of 800 through two-dimensional numerical simulations. These fluid dynamics simulations were…
Oscillating foil turbines (OFTs) can be used to produce power from rivers and tides by synchronizing their heaving motion with the strong lift force of vortices shed at their leading edge. Prior work has shown that compliant membrane OFTs,…
The present paper numerically investigates flow control over NACA0021 (National Advisory Committee for Aeronautics) airfoil by applying a leading-edge tubercle as a passive flow control device at transitional Reynolds number (Re) regime.…
High-speed water entry of projectiles and diving systems induces high forces and jerk to the entering bodies due to the development of large hydrodynamic pressure. Previous research has shown separately that the peak forces can be reduced…