Shantanu Shrinath Bhat

UNSW Canberra

The wing aspect ratio (AR), that is, the ratio of the wingspan to the mean wing chord, is the most important geometrical parameter describing an insect wing. While studies have shown that a change in AR affects the flow structure as well as the aerodynamic force components on wings, the reasons behind the wide variety of aspect ratios observed in n...

The aerodynamic performance of an insect wing is largely dependent on the leading-edge vortex (LEV) on the wing formed during the rotational translation phase of its flapping motion. The geometry of the wing can directly influence the formation and strength of the LEV. The wing geometry is broadly defined by the aspect ratio and the radii of the wi...

The power exchange between fluid and structure plays a significant role in the force production and flight efficiency of flapping wings in insects and artificial flyers. This work numerically investigates the performance of flapping wings by using a high-fidelity fluid-structure interaction solver. Simulations are conducted by varying the hinge fle...

The potential application of flapping wings in micro-aerial vehicles is gaining interest due to their ability to generate high lift even in confined spaces. Most studies in the past have investigated hovering wings as well as those flapping near solid surfaces. However, the presence of surface tension at the water-air interface and the ability of t...

Autonomous blimps have potential applications in surveillance, monitoring, and advertising. Due to their lower payload capacities and possible unstable flight profile, small blimps have been mostly used in indoor applications. However, recent advancements in their design and control have increased the prospects of deploying them for outdoor applica...

Low-aspect-ratio revolving wings find applications in miniature robotic flyers and turbo-machinery. At a high angle of attack, the flow separates from a wing's leading edge, forming a leading-edge vortex. On a revolving wing, the leading-edge vortex (LEV) is stabilized by strong rotational acceleration and is known to be the primary source of high...

A wing at a constant angle of attack (α 0), rotating with a constant angular velocity (Ω), is known to experience stable lift and drag forces as a result of a stably attached leading-edge vortex (LEV) formed over the leading edge. The present experiments on a rectangular wing rotating at Re = 2500 show that, when the pitch angle (α) of the wing is...

Coherent structures in a turbulent boundary layer have been shown to have an influence on the skin-friction drag acting on surfaces beneath the boundary layer. The use of micro-cavities on a flat surface has recently shown the potential to passively control a turbulent boundary layer by attenuating the sweep events. Previous experiments have determ...

The turbulence intensities and shear stresses in a turbulent boundary layer (TBL) are primarily associated with the presence of coherent structures, such as sweep and ejection events. Recent experiments using a passive method of controlling the TBL using micro-cavities have reported a reduction in the coherent structures by ∼ 7%. However, the mecha...

Flapping wings of insects can follow various complex-motion waveforms, influencing the flow structures over a wing and consequently the aerodynamic performance. However, most studies of insect-wing models incorporate either simple harmonic or robofly-like motion waveforms. The effects of other waveforms appear to be under-explored. Motivated by thi...

The flow over an insect wing can be highly influenced by the wing aspect ratio (A), affecting the aerodynamic forces. Previous studies present apparently contradictory effects of A, creating a challenge in selecting the optimum A in the design of insect-inspired micro air vehicles. Some recent studies indicate that the A-effects are coupled with th...

Wing shape is an important factor affecting the aerodynamic performance of wings of monocopters and flapping-wing micro air vehicles. Here, an evolutionary structural optimisation method is adapted to optimise wing shape to enhance the lift force due to aerodynamic pressure on the wing surfaces. The pressure distribution is observed to vary with th...

The individual and combined influences of aspect ratio ( $A$ ), Reynolds number ( $Re$ ) and Rossby number ( $Ro$ ) on the leading-edge vortex (LEV) of a rotating wing of insect-like planform are investigated numerically. A previous study from our group has determined the wingspan to be an appropriate length scale governing the large-scale LEV stru...

Further advances in the design of micro air vehicles (MAVs) may require detailed understanding of the aerodynamics of the flapping wings of insects, which outperform the lifting mechanisms used in standard MAVs. Researchers in the past have proposed different mechanisms in order to explain the higher lift observed for insect wings flapping at very...

Stable attachment of a leading-edge vortex (LEV) plays a key role in generating the high lift on rotating wings with a central body. The central body size can affect the LEV structure broadly in two ways. First, an overall change in the size changes the Reynolds number, which is known to have an influence on the LEV structure. Second, it may affect...

Discrepancies exist in the effects of aspect ratio on the lift coefficient (CL) of insect wings reported in past studies. CL is found to be affected by the aspect ratio, Reynolds number and Rossby number - studied over a large parameter space. The large scale vortex structure over a wing is found to scale with the wing span. The Reynolds number and...

The stable attachment of a leading-edge vortex (LEV) is responsible for the high lift observed from insect wings. In experiments, we study the flow structure over a model wing mounted on a central body. The diameter of the central body and the change in Rossby number (Ro) due to placement of the wing root away from the centre can affect the flow st...

Stable attachment of the Leading Edge Vortex (LEV) is a peculiar aspect of aerodynamics of flapping wings of insects providing much higher lift than that from the aircraft wings. Parameters such as wing aspect ratio (AR), Reynolds number (Re), advance ratio and wing flexibility play an important role in determining the stability of a LEV. In our pr...

Stable attachment of the Leading Edge Vortex (LEV) is responsible for stable flight in insects. The LEV structure over a flapping insect wing is influenced by several geometrical and kinematic parameters. In our study, it is shown that a change in the wing Reynolds number (Re) affects the LEV structure. A comparison with previous numerical results...

Highly-loaded turbomachine blades can stall under off-design conditions. In this regime, the flow can separate close to the leading edge of the blade resulting in periodic formation of vortices that can lead to blade vibrations, commonly referred to as stall flutter. Towards understanding this phenomenon, we experimentally study the propensity of a...