渦対の形成過程の現実的数値シミュレーション(流体数理(1),一般講演)

概要

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Formation of a vortex pair or ring from a nozzle by piston motion is regarded as one of the simplest and the most fundamental processes of vortex formation. However, in the experiments it is difficult to obtain vorticity distribution without certain amount of errors while in most of the numerical simulations the piston motion is only implicitly taken into account by imposing the inlet velocity profile. In this paper we perform a realistic direct numerical simulation of the vortex pair formation with high accuracy. The piston motion is explicitly taken into account by the volume penalization method. The two-dimensional incompressible Navier-Stokes equations are solved by the volume penalization method. For spatial differentiation the compact scheme is used for an open flow direction and the Fourier spectral method is used for the other direction. The results reveal the details of the formation process and the vorticity distribution of a vortex pair observed in the experiments. For Re=2300, L/D=1.4 the symmetric mode is close to Gaussian. The dipole and strain component are also observed.
日本流体力学会の論文
2010-09-09