Parametric study of an acoustic levitation system

Oran, W. A.; Bergé, Luc; Parker, H. W.

doi:10.1063/1.1136268

Cited by 43 publications

(10 citation statements)

References 3 publications

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“…[1][2][3][4][5] The technique has already been applied in fluid dynamics, 6 material sciences, 7 and analytical chemistry. 8 The ultrasound transducer of an acoustic levitator that vibrates in the direction perpendicular to its surface emits a sound wave that, if reflected from a similar surface at a distance d, results in a standing acoustic wave.…”

Section: Sigurd Bauerecker A) and Bernd Neidhartmentioning

confidence: 99%

Formation and growth of ice particles in stationary ultrasonic fields

Bauerecker¹,

Neidhart²

1998

The Journal of Chemical Physics

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The formation of ice particles in stationary ultrasonic fields (SUSFs) from ice aerosol was observed. Under suitable experimental conditions aerosol particles gather in stable ellipsoidal systems at temperatures down to <50 K below ambient. We call these systems cold gas traps. The aerosol concentrates in the pressure node areas of the SUSF and conglomerates to form larger particles and snowflakes with diameters up to 10 mm. The resulting shapes are shown. Most of them are similar to those occurring in nature. An attempt is made to explain the effect. Three different processes of ice particle formation are visualized and discussed. Here the existence of a quasiliquid layer (QLL) on the particle surfaces seems to be essential because both the formation of ice particles and the QLL occur only at temperatures higher than about −25 °C. The observed trapping and generation process can be used, for example, in atmospheric physics for the study of particle aggregation, precipitation formation, and water and radiation transport phenomena.

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Section: Sigurd Bauerecker A) and Bernd Neidhartmentioning

confidence: 99%

Formation and growth of ice particles in stationary ultrasonic fields

Bauerecker¹,

Neidhart²

1998

The Journal of Chemical Physics

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“…0,1-10 mm große Partikel in den Druckknoten eines stehenden Ultraschallfeldes berührungsfrei zu levitieren. Dieser Effekt wurde in den 1970er und 1980er Jahren von der NASA und ESA aufgegriffen und zur technischen Reife gebracht [2] und unter Mikrogravitationsbedingungen in Weltraumlabors dazu verwendet, um kleine Proben ortsfest zu positionieren. Mittlerweile wird die Technik auch bei den Gravitationsbedingungen auf der Erde zur berührungslosen Probenhalterung genutzt.…”

Section: Da S E Xperimentunclassified

Wie akustische Kaltgasfallen wirken. “Tannenbäume” im stehenden Ultraschallfeld

Tuckermann

Bauerecker

2008

Chemie in nserer Zeit

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Der Kaltgasfalleneffekt ermöglicht den Einfang von kalten (bzw. schweren) Gasen und Aerosolen in starken, stehenden Ultraschallfeldern. Der Effekt kann mit klassischen akustischen Prinzipien verstanden werden. Man kann ihn kontrolliert nutzen, um Temperaturen bis zu –100 °C in den Bereichen der Druckknoten eines stehenden Ultraschallfeldes (und somit in der unmittelbaren Umgebung einer levitierten Probe) zu erzeugen. Diese Kaltgas‐ und Aerosolfallen werden hier mit einem besonders leistungsstarken Levitator generiert. In ihnen lassen sich beispielsweise die Bildung und das Wachstum von Eis‐ und Schneepartikeln aus primärem Eisaerosol untersuchen, ebenso wie Gefrier‐ und Schmelzprozesse an einzelnen berührungsfrei levitierten Wassertropfen. Mit Hilfe von Hochgeschwindigkeitskameras (VIS, IR) lässt sich die schnelle erste Stufe der Eisbildung an schwebenden unterkühlten Tropfen erforschen.

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“…[3][4][5][6] This containerless material-handling technique is a good candidate to circumvent difficulties in research with interfering container surfaces, 7,8 or long response times in bulk experiments. 9 Axisymmetric levitators, developed to suspend and keep objects at one location, have been the focus of intense research interest.…”

Section: Introductionmentioning

confidence: 99%

Acoustic levitator for contactless motion and merging of large droplets in air

Bjelobrk

Nabavi

Poulikakos

2012

Journal of Applied Physics

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Flow and noise predictions for the tandem cylinder aeroacoustic benchmark Phys. Fluids 24, 036101 (2012) Acoustic cloak for airborne sound by inverse design Appl. Phys. Lett. 99, 074102 (2011) Influence of gases on Lamb waves propagations in resonator Appl. Phys. Lett. 95, 223505 (2009) Sound control by temperature gradients Appl. Phys. Lett. 95, 204102 (2009) Quenching of acoustic bandgaps by flow noise Appl. Phys. Lett. 94, 134104 (2009) Additional information on J. Appl. Phys.Large droplet transport in a line-focussed acoustic manipulator in terms of maximum droplet size is achieved by employing a driving voltage control mechanism. The maximum volume of the transported droplets in the order of few microliters is thereby increased by three orders of magnitude compared to the constant voltage case, widening the application field of this method significantly. A drop-on-demand droplet generator is used to supply the liquid droplets into the system. The ejected sequence of picoliter-size droplets is guided along trajectories by the acoustic field and accumulates at the selected pressure node, merging into a single large droplet. Droplet movement is achieved by varying the reflector height. This also changes the intensity of the radiation pressure during droplet movement, which in turn could atomise the droplet. The acoustic force is adjusted by regulating the driving voltage of the actuator to keep the liquid droplet suspended in air and to prevent atomisation. In the herein presented levitation concept, liquids with a wide range of surface tension (water and tetradecane were tested) can be transported over distances of several mm. The aspect ratio of the droplet in the acoustic field is shown to be a good indicator for radiation pressure intensity and is kept between 1.1 and 1.4 during droplet transport. Despite certain limitations with volatile liquids, the presented acoustic levitator concept has the potential to expand the range of analytical characterisation and manipulation methods in applications ranging from chemistry and biology. V C 2012 American Institute of Physics. [http://dx.

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Parametric study of an acoustic levitation system

Cited by 43 publications

References 3 publications

Formation and growth of ice particles in stationary ultrasonic fields

Formation and growth of ice particles in stationary ultrasonic fields

Wie akustische Kaltgasfallen wirken. “Tannenbäume” im stehenden Ultraschallfeld

Acoustic levitator for contactless motion and merging of large droplets in air

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