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  Acoustic radiation around cascad of flat plates

 The aerodynamic noise generated from the
cascade of blades often becomes a problem in an
automobile and a heat exchange system. The most
instense sound is radiated when the frequency of the
vortex shedding from the blades matches that of the
acoustic resonance between the blades.

Acoustic waves and vortices around flat plates
Publications
1. Hiroshi Yokoyama, Katsuya Kitamiya, and Akiyoshi Iida, "Flows around a cascade of flat plates with acousticsresonance",25(10), 106104, 2013. PDF
(Copyright (2013) American Institute of Physics. This article may be downloaded for personal use only. Any other userequires prior permission of the author and the American Institute of Physics:This article may be found at AIP).

  Cavity tone

 Radiation of cavity tones by the self-sustainedoscillations with the fluid-acoustic interactionsbecomes a problem in a high-speed train etc.
 Our objective is to clarify the mechanism of theradiation and establish the decrease technique ofthe cavity tones. The direct computations and windtunnel experiments of the simultaneousmeasurements of the flow and sound are done.

Vortices and acoustic
waves (DNS)



Visualized flow

Publications
1. Hiroshi Yokoyama and Chisachi Kato, Fluid-Acoustic Interactions in Acoustic Radiation in Turbulent Cavity Flows (Fluid-Dynamic Oscillations),Journal of Environment and Engineering,6(1), pp. 90-106 (2011).J-STAGE
2. Hiroshi Yokoyama and Chisachi Kato, "Fluid-acoustic interactions in self-sustainedoscillations in turbulent cavity flows. I.Fluid-dynamic oscillations,"Physicsof Fluids21, 105103 (2009).AIP


  Fan noise

 In order to establish the methods for the prediction
of the aerodynamical noise radiating from fans, the
hybrid computations of incompressible flow simulation
and acoustic simulation are performed.

Streamwise velocity

Vortices




Flow and sound around musical instruments

 To clarify the mechanism of acoustic radiation and propagation, direct simulations of flow and acoustic fields and experiments by using PIV are performed.
Vortices near edge

Acoustic field
Appear in New Scientist, February 2015
"See how sound radiates around a recorder"

Press release (English)

Interior noise of automobiles

 To predict interior noise of automobiles due to the noise from various parts outside, the simulations and experiments are performed.
Vortices in wake

Acoustic waves radiatingfrom side mirror