Heat transfer enhancement in a channel flow using two wall-mounted flexible flags with a confined cylinder

Jeong, Young Dal; Ahn, Ki Ho; Kim, Min Je; Lee, Jae Hwa

doi:10.1016/j.ijheatmasstransfer.2022.123185

Cited by 6 publications

(2 citation statements)

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“…2017; Jeong et al. 2022). A flag, which is considered to be an elastic sheet with a fixed front end and a free rear end, exhibits distinct behaviours depending on the flow conditions and material properties, ranging from a stable equilibrium state to an unstable postcritical state.…”

Section: Introductionmentioning

confidence: 99%

“…Ellis, Williams & Shneerson 1993;Ristroph & Zhang 2008;Ryu et al 2019;Zhang, Huang & Lu 2020;Yang et al 2021) and industrial phenomena such as the production of papers or films and flow control devices for convective heat transfer (e.g. Watanabe et al 2002;Shoele & Mittal 2014;Park et al 2016;Lee et al 2017;Jeong et al 2022). A flag, which is considered to be an elastic sheet with a fixed front end and a free rear end, exhibits distinct behaviours depending on the flow conditions and material properties, ranging from a stable equilibrium state to an unstable postcritical state.…”

Section: Introductionmentioning

confidence: 99%

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Gravity-coupled flutter and contact of a flag near a wall

Lee,

Jung,

Lee

et al. 2023

J. Fluid Mech.

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The stability and postcritical behaviour of a horizontal flag undergoing gravity-induced deformation and periodic contact with a nearby horizontal rigid wall are experimentally investigated. The results elucidate the combined effects of gravity and contact on flutter, and reveal design principles for application to triboelectric energy harvesting. By varying the free-stream velocity, flag thickness and distance between the flagpole and the wall, the dynamics of the flag are classified into quasistatic equilibrium, flutter, partial contact and saturated contact modes. Considering the significance of gravitational effects, a new dimensionless flow velocity is proposed to identify the distribution of the dynamic modes, and its definition varies according to whether the wall is placed above or below the flag. The critical conditions for transitions between the dynamic modes are determined from the balance of fluid dynamic and gravitational effects. The distance from the flagpole to the wall is found to be more critical for transitions in the lower-wall configuration than in the upper-wall configuration. The peak contact force as well as the oscillation amplitude and frequency at postequilibrium exhibits remarkably different trends depending on the location of the wall. The peak contact force imposed on the wall by the fluttering flag weakens as the distance to the wall increases in the case of an upper wall, whereas it becomes stronger in the case of a lower wall.

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Section: Introductionmentioning

confidence: 99%