The role of vortex–vortex interactions in thrust production for a plunging flat plate

Rahman, Aevelina; Tafti, Danesh K.

doi:10.1016/j.jfluidstructs.2020.103011

Cited by 7 publications

(3 citation statements)

References 25 publications

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“…The in-house Navier–Stokes solver has been used and validated for a diverse field of applications like bio-locomotion [ 54 ], bio-fluid mechanics [ 55 ], multiphase fluid-particulate system [ 56 ], turbo-machinery [ 57 , 58 ], heat transfer augmentation [ 59 ], etc. The IBM formulation specifically has been validated and applied to many different geometries and flow conditions, (e.g.…”

Section: Methodsmentioning

confidence: 99%

Turning-ascending flight of a Hipposideros pratti bat

2022

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Bats exhibit a high degree of agility and provide an excellent model system for bioinspired flight. The current study investigates an ascending right turn of a Hipposideros pratti bat and elucidates on the kinematic features and aerodynamic mechanisms used to effectuate the manoeuvre. The wing kinematics captured by a three-dimensional motion capture system is used as the boundary condition for the aerodynamic simulations featuring immersed boundary method. Results indicate that the bat uses roll and yaw rotations of the body to different extents synergistically to generate the centripetal force to initiate and sustain the turn. The turning moments are generated by drawing the wing inside the turn closer to the body, by introducing phase lags in force generation between the wings and redirecting force production to the outer part of the wing outside of the turn. Deceleration in flight speed, an increase in flapping frequency, shortening of the upstroke and thrust generation at the end of the upstroke were observed during the ascending manoeuvre. The bat consumes about 0.67 W power to execute the turning-ascending manoeuvre, which is approximately two times the power consumed by similar bats during level flight. Upon comparison with a similar manoeuvre by a Hipposideros armiger bat (Windes et al . 2020 Bioinspir. Biomim . 16 , abb78d. ( doi:10.1088/1748-3190/abb78d )), some commonalities, as well as differences, were observed in the detailed wing kinematics and aerodynamics.

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Section: Methodsmentioning

confidence: 99%

Turning-ascending flight of a Hipposideros pratti bat

2022

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“…An in-house incompressible Navier-Stokes solver, GenIDLEST [55] is used to simulate the aerodynamic flow around the bat during all the flights. This solver has been utilized and validated for a diverse field of applications like bio-inspired locomotion [56], bio-fluid mechanics [57], multiphase fluidparticulate system [58], turbo-machinery [59,60], heat transfer augmentation [61] etc. The immersed boundary method (IBM) is used to resolve the wing motion which is represented by a triangulated surface mesh immersed in a background volumetric mesh.…”

Section: Aerodynamic Analysismentioning

confidence: 99%

Role of wing inertia in maneuvering bat flights

Rahman¹,

Tafti²

2022

Bioinspir. Biomim.

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The individual effects of aerodynamics and wing inertia on the motion dynamics for maneuvering flight of two species of roundleaf bats, H. armiger and H. pratti bats have been investigated. Comparative studies among a straight flight, two ascending right turns, and a U-turn reveal that inertial forces play an essential and sometimes crucial role in effecting the maneuvers. The maneuvering trajectory of the bat is mostly driven by the aerodynamic forces generated by the wings along the flight path, whereas inertial forces for the most part drive the intra-cycle fluctuations. Inertial forces were also found to contribute non-trivially to the ascending motion of the H. armiger. Similar to translation, while aerodynamic moments account for the general rotational trends in roll, pitch and yaw angles exhibited by the bat body, inertial moments influence intra-cycle fluctuations. In addition, inertial moments play a dominant and crucial role for effecting yaw rotation during maneuvers for the sweeping turns as well as the U-turn. The moment resulting from the Coriolis force is deemed essential in accurate yaw prediction for lateral maneuvers. Finally, as the maneuver gets more complex or extreme such as in a 180° U-turn, the importance of the Coriolis and centrifugal moments increase, with the largest effect of centrifugal moments evidenced in the U-turn.

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“…Karbasian and Kim [37] revealed that despite the existence of coherent structures, the interaction of organized vortices is responsible for the complexity of the flow in stall. What's more, Rahman and Tafti [38] gave a more direct explanation that LEVs were responsible for the production of thrust whereas TEVs led to drag. Zhou et al [39] paid more attention to the boundary layer characteristics near TE.…”

Section: Nomenclature αmentioning

confidence: 99%