Abstract
Acoustic microstreaming is a nonlinear response of a fluid that undergoes high-amplitude acoustic stimulation and tends to viscously absorb it. The present experimental study investigates the generation of acoustic microstreaming induced by an oscillating wall-attached bubble undergoing nonspherical shape modes. From a microscope top view, the formation of particular flow signatures is explored for the main classes of spherical harmonics
$Y_{nm}(\theta, \phi )$
: zonal (
$m = 0 < n$
), sectoral (
$n = m > 0$
) and tesseral (
$0 < m < n$
) oscillation. The microstreaming induced by a bubble animated by a sectoral mode alone reveals a pattern characterized by a
$4n$
-lobe flower shape. Tesseral modes give rise to 4m-lobe flower-shaped patterns. Finally, when sectoral and zonal modes coexist, two kinds of pattern stand out:
$2n$
-lobe flower shape and
$n$
-pointed star shape. The preferential emergence of one or another streaming pattern is discussed on the basis of the amplitude and phase shift between both shape modes.
Funder
Centre Lyonnais d'Acoustique, Université de Lyon
Publisher
Cambridge University Press (CUP)
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics
Cited by
1 articles.
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