A221 壁乱流の渦から出る音の DNS

概要

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Our objective is to make clear the key element of sound source in turbulent flow near a wall and to realize the noise reduction emitted from them. Thus it is needed to define appropriate indice of sound source, in case of low Mach number flow, we have revealed that the second time derivative of incompressible pressure fluctuation is good measure in source field, which has been proposed by Ribner (1963). Then using the DNS data base of turblent channel flow, the indice of sound source is visualized in near wall region. As a result it is revealed that coherent structures of streamwise vortices and larger scale hair-pin-like vortices are responsible for turbulent noise. Furthermore acoustic field is simulated numerically by DNS code based on Hardin & Pope scheme, it is observed that coherent bubble-like structures of acoustic pressure are produced further away from the wall although the broad-band feature of frequency spectra suggests accoustic field being in disorder.
日本流体力学会の論文
2000-07-25