Method of evaluating dipole sound source in a finite computational domain

DOI PDF 被引用文献11件
  • T. Takaishi
    Railway Technical Research Institute, Tokyo, 185-8540, Japan
  • M. Ikeda
    Railway Technical Research Institute, Tokyo, 185-8540, Japan
  • C. Kato
    Institute of Industrial Science, University of Tokyo, Tokyo, 153-8505, Japan

抄録

<jats:p>Numerical prediction of dipole sound based on Lighthill–Curle’s equation gives little information on the structure of sound sources. On the other hand, a hybrid method that combines the large eddy simulation (LES) and the compact Green’s function proposed by Howe provides detailed information on the vortices in the flow that most contribute to the generation of sound. However, when the dipole sound is evaluated from the momentum change in fluid inside a finite computational domain, the result does not in general agree with the sound evaluated from the fluctuating pressure on the body surface because contribution from vortices outside the computational domain is not taken into account. In this study, the balance of momentum in a finite computational domain is considered strictly, and the effect of outer vortices is replaced with contribution from inner properties by using an imaginary velocity potential φi. This process avoids sudden termination of Lighthill’s stress tensor at the outer boundary and extracts the net contribution from dipole sound sources. With this new method, this paper simulates dipole sound sources around pantograph horns numerically, and clarifies how strong dipole sound sources are formed in the shear layer close to the model surface and how the flow through holes plays an important role in cancellation of sound sources.</jats:p>

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