Three-dimensional transient flows past plates translating near a wall

Liu, I-Han; Öztekin, Alparslan

doi:10.1016/j.oceaneng.2018.04.023

Cited by 2 publications

(2 citation statements)

References 37 publications

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“…We next consider flows past a single plate and an array of tandem plates of 90º corner angle operating beneath a rigid wall, H B = 8D and H T = 0.1D, to elucidate the capability of the FTLE fields in detecting LCSs at another fluid-structure interaction scenario. This type of flow involves highly complex vortex dynamics due to the interaction between the boundary layer and the plate(s) [27]. The FTLE fields are The FTLE and the instantaneous Q-criterion contours for the two tandem plates near a wall are presented in Fig.…”

Section: Flows Past Arrays Of Plates In the Vicinity Of Surfacesmentioning

confidence: 99%

“…The experimental study by Yen et al [25] using two tandem square cylinders placed in a vertical water tank showed that multiple shedding modes occur depending on different spacing and spatial position of the downstream cylinder. Sohankar [26] studied the wake flow interaction between two square cylinders in a tandem arrangement by conducting Large Eddy Simulations [27] studied flows past arrays of a finite plate placed near the rigid surfaces using LES. They reported that the drag forces decrease rapidly when the plate is situated very close to the wall.…”

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Vortex identification in turbulent flows past plates using the Lagrangian method

et al. 2019

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Vortex identifications in turbulent flows past arrays of tandem plates are performed by employing the velocity field obtained by high-fidelity large eddy simulations. Lagrangian coherent structures (LCSs) are extracted to examine the evolution and the nonlinear interaction of vortices and to characterize the spatial and temporal characteristics of the flow. LCSs’ identification method is based on the finite-time Lyapunov exponent (FTLE), which is evaluated using the instantaneous velocity data. The simulations are performed in three-dimensional geometries to understand the physics of fluid motion and the vortex dynamics in the vicinity of plates and surfaces at Reynolds number of 50 000. The instantaneous vorticity fields, Eulerian Q-criterion, and LCSs are presented to interpret and understand complex turbulent flow structures. The three-dimensional FTLE fields provide valuable information about the vortex generation, spatial location, evolution, shedding, decaying, and dissipation of vortices. It is demonstrated here that FTLE can be used together with Eulerian vortex identifiers to characterize the turbulent flow field effectively.

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Section: Flows Past Arrays Of Plates In the Vicinity Of Surfacesmentioning

confidence: 99%

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Vortex identification in turbulent flows past plates using the Lagrangian method

et al. 2019

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Flow development over inclined flat plates in ground effect and relation to aerodynamic loads

2022

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The aerodynamics of finite-span inclined flat plates in ground effect is experimentally investigated at a chord-based Reynolds number of 50 000 for aspect ratios of 1 and 2. The minimum ground height is varied between 0.1 and 1.0 chord lengths, and lift and drag forces are measured using a force balance for angles of attack between −90° and 90°. Planar, two- and three-component particle image velocimetry is used to perform streamwise and cross-plane measurements at the midspan and one chord length downstream of the trailing edge, respectively. Ground effect is significant at ground clearances below 0.5 chord lengths, most notably near the stall angle, where it leads to significant changes to flow development. At sufficiently low free flight pre-stall angles, the increase in edge velocity at low gap ratios caused greater suction, generating higher lift with a minimal increase in drag for both orientations. Closer to the free flight stall angle, a decrease in aerodynamic loading is observed for negative orientations due to earlier onset of stall with a decreasing gap ratio. The exception was the higher aspect ratio plate at negative orientations, where the loading was largely invariant to changes in gap ratio for all angles tested. At positive orientations, the increase in average static pressure along the pressure surface in ground proximity led to an overall increase in loading prior to deep-stall conditions for both aspect ratios. The ground effect was minimal at post-stall angles of attack. The results may be used to guide the design of photovoltaic supports at relevant latitudes.

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Three-dimensional transient flows past plates translating near a wall

Cited by 2 publications

References 37 publications

Vortex identification in turbulent flows past plates using the Lagrangian method

Vortex identification in turbulent flows past plates using the Lagrangian method

Flow development over inclined flat plates in ground effect and relation to aerodynamic loads

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