High Reynold Number LES of a Rotating Two-Pass Ribbed Duct

Tafti, Danesh K.; Dowd, Cody; Tan, Xiao

doi:10.3390/aerospace5040124

Cited by 12 publications

(2 citation statements)

References 109 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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Direct Numerical Simulation of Turbulent Flow in a Circular Pipe Subjected to Radial System Rotation

Zhang

Wang

2019

Flow Turbulence Combust

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In this thesis, direct numerical simulations have been preformed with a high-order spectral element method computer code to investigate the Coriolis force effect on a fully-developed turbulent flow confined within a circular pipe subjected to radial system rotations. In order to study the radially rotating effects on the flow, a wide range of rotation numbers (Ro τ ) have been tested. In response to the system rotation imposed, large-scale secondary flows appear as streamwise counter-rotating vortices, which highly interact with the boundary layer and have a significant impact on the turbulent flow structures and dynamics. A quasi Taylor-Proudman region occurs at low rotation numbers, where the mean axial velocity is invariant along the rotating axis. As the rotation number increases, laminarization occurs near the bottom wall of the pipe, and the flow become fully laminarized when the rotation number approaches Ro τ = 1.0. The characteristics of the flow field are investigated in both physical and spectral spaces, which include the analyses of the first-and second-order statistical moments, pre-multiplied spectra of velocity fluctuations, budget balance of the transport equation of Reynolds stresses, and coherent flow structures. i Acknowledgements I would like to express my great gratitude to my supervisor Prof. Bing-Chen Wang for his encouragement, support and guidance, and also for his experience and suggestions in social communication which was very helpful to me on how to conduct myself during my M.Sc. study in Canada. I would also like to express my appreciation to Dr. Xing-Jun Fang for his generous help and guidance on my M.Sc. study and project during his PhD program.

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High Reynold Number LES of a Rotating Two-Pass Ribbed Duct

Cited by 12 publications

References 109 publications

Turning-ascending flight of a Hipposideros pratti bat

Turning-ascending flight of a Hipposideros pratti bat

Role of wing inertia in maneuvering bat flights

Direct Numerical Simulation of Turbulent Flow in a Circular Pipe Subjected to Radial System Rotation

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