Coupling mechanical rotation and EHD actuation in flow past a cylinder

Gronskis, Alejandro; D’Adamo, Juan; Artana, Guillermo; Camillieri, A.; Silvestrini, Jorge Hugo

doi:10.1016/j.elstat.2007.06.007

Cited by 8 publications

(2 citation statements)

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“…A number of experimental and numerical studies have been directed toward controlling the flow separation due to its fundamental importance in various applications. − Experimentally, several passive techniques have been investigated for controlling flow separation . The relative effect of these techniques on separation has been studied by using surface static-pressure measurements as well as surface oil flow visualizations.…”

Section: Introductionmentioning

confidence: 99%

Unraveling Flow Separation at the Water–Carbon Nanotube Interface: An Atomic-Scale Overview by Molecular Dynamics Simulation

2022

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Flow separation near the fluid–solid surface has attracted attention for decades. It is critical to understand the behavior of separated flow adjacent to the solid walls to broaden its range of potential applications. Therefore, we conducted molecular dynamics investigations to consider water flow separation at the water–carbon nanotube (CNT) interface for different diameters of CNTs between 13 and 50 Å and different pressures of 0.1–1.254 GPa. Density heat maps indicated that water flow separation is observed for all CNTs under high pressures, and an empty space of water molecules or evacuation is formed behind the CNTs. It is shown that in CNTs with small diameters, (10, 10) and (20, 20), the structure of the first layer (FL) of water molecules or hydrated layer adjacent to the CNT wall is completely preserved, indicating that evacuation occurs from behind the CNTs. In (30, 30) and (40, 40) CNTs, flow separation occurred from the FL of water molecules near the solid surface, and the layered structure of water around CNTs is completely destroyed. Our findings of fluid–solid and fluid–fluid interaction energies suggested that the flow separation can be due to an attraction between the FL of water molecules and CNT and a repulsion between the water molecules in the hydrated layer and the outer layers. Moreover, analyzing the relationship between the CNT size and flow separation revealed that in the case of small CNTs, there are extra water molecules that contribute to the structural stability of the hydrated layer by strengthening the repulsive interaction in the liquid–liquid surface.

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Section: Introductionmentioning

confidence: 99%

Unraveling Flow Separation at the Water–Carbon Nanotube Interface: An Atomic-Scale Overview by Molecular Dynamics Simulation

2022

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“…boundary condition. Along these lines, the work of Gronskis (2009), Gronskis et al (2009), and other authors (Peers et al 2009) analyzed numerical models of DBD forced flows around cylinders at low Reynolds numbers (Re < 200).…”

Section: Introductionmentioning

confidence: 99%

The scenario of two-dimensional instabilities of the cylinder wake under electrohydrodynamic forcing: a linear stability analysis

D’Adamo¹,

González²,

Gronskis³

et al. 2012

Fluid Dyn. Res.

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We propose to study the stability properties of an air flow wake forced by a dielectric barrier discharge (DBD) actuator, which is a type of electrohydrodynamic (EHD) actuator. These actuators add momentum to the flow around a cylinder in regions close to the wall and, in our case, are symmetrically disposed near the boundary layer separation point.Since the forcing frequencies, typical of DBD, are much higher than the natural shedding frequency of the flow, we will be considering the forcing actuation as stationary.In the first part, the flow around a circular cylinder modified by EHD actuators will be experimentally studied by means of particle image velocimetry (PIV). In the second part, the EHD actuators have been numerically implemented as a boundary condition on the cylinder surface. Using this boundary condition, the computationally obtained base flow is then compared with the experimental one in order to relate the control parameters from both methodologies.After validating the obtained agreement, we study the Hopf bifurcation that appears once the flow starts the vortex shedding through experimental and computational approaches. For the base flow derived from experimentally obtained snapshots, we monitor the evolution of the velocity amplitude oscillations. As to the computationally obtained base flow, its stability is analyzed by solving a global eigenvalue problem obtained from the linearized Navier-Stokes equations. Finally, the critical parameters obtained from both approaches are compared.

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