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Hovering of a rigid pyramid in an oscillatory airflow

Published online by Cambridge University Press:  19 March 2010

ANNIE WEATHERS ,
BRENDAN FOLIE ,
BIN LIU ,
STEPHEN CHILDRESS  and
JUN ZHANG
ANNIE WEATHERS
Affiliation:
Department of Physics, New York University, 4 Washington Place, New York, NY 10003, USA
BRENDAN FOLIE
Affiliation:
Department of Mathematics, Harvey Mudd College, 301 Platt Boulevard, Claremont, CA 91711, USA
BIN LIU*
Affiliation:
Applied Mathematics Laboratory, Courant Institute, New York University, 251 Mercer Street, New York, NY 10012, USA
STEPHEN CHILDRESS
Affiliation:
Applied Mathematics Laboratory, Courant Institute, New York University, 251 Mercer Street, New York, NY 10012, USA
JUN ZHANG
Affiliation:
Department of Physics, New York University, 4 Washington Place, New York, NY 10003, USA Applied Mathematics Laboratory, Courant Institute, New York University, 251 Mercer Street, New York, NY 10012, USA
*
†Email address for correspondence: [email protected]
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Abstract

We investigate the dynamics of rigid bodies (hollow ‘pyramids’) placed within a background airflow, oscillating with zero mean. The asymmetry of the body introduces a net upward force. We find that when the amplitude of the airflow is above a threshold, the net lift exceeds the weight and the object starts to hover. Our results show that the objects hover at far smaller air amplitudes than would be required by a quasi-steady theory, although this theory accounts qualitatively for the behaviour of the system as the body mass becomes small.

Type
Papers
Information
Journal of Fluid Mechanics , Volume 650 , 10 May 2010 , pp. 415 - 425
Copyright
Copyright © Cambridge University Press 2010

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