Dynamical modelling of the flow over a flapping wing using proper orthogonal decomposition and system identification techniques

Durmaz, Oguz; Karaca, Hulusi; Ozen, Guzide; Kasnakoğlu, Coşku; Kurtuluş, Dilek Funda

doi:10.1080/13873954.2012.705859

Cited by 4 publications

(1 citation statement)

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“…Findings of these studies were reported based on the time series of forces, non-dimensional force coefficients or their cycle averaged values. The onset of unstable behaviour in flapping wing systems due to gust was explained using numerical visualization techniques like surface pressure contours, 2D or 3D streamlines, vorticity contours, Q-criteria, k 2 criteria, Lagrangian coherent structures [33] or proper orthogonal decomposition [34]. Some of these approaches are computationally expensive.…”

Section: Introductionmentioning

confidence: 99%

Recurrence studies of insect-sized flapping wings in inclined-stroke plane under gusty conditions

Mathur

Vengadesan

2019

Sādhanā

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Global recurrence plots (GRPs) and windowed recurrence quantification analysis (WRQA) are two recurrence paradigms which find wide applications to detect the onset of instability in a dynamic system. The present work reports the attempt to employ these recurrence paradigms to assess the effect of frontal gust on the force patterns of an insect-sized flapping wing in the inclined-stroke plane. Horizontal and vertical forces generated by the flapping wing in the presence of gusts of the form u G u w ¼ u 1 u w þ u g u w sin 2p f g f w t were numerically estimated in the 2D reference frame for Re = 150. Nine gusts with combinations of the ratio of gust frequency to wing's flapping frequency, f g /f w = 0.1, 0.5 and 1 and ratio of gust velocity amplitude to root mean square averaged flapping velocity, u g /u w = 0.1, 0.5 and 1 were considered. Recurrence studies of the forces were carried out to find out the gusty condition, which would trigger an onset of unstable behaviour. Studies indicated a possible onset of instability in the force patterns for gust with f g /f w = 0.1 and u g /u w = 1. The onset of unstable behaviour was prominently captured by WRQA of the vertical force coefficient based on determinism (DET) and laminarity (LAM) series.

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Section: Introductionmentioning

confidence: 99%