抄録
Large-eddy simulations are performed for hyperbolic stagnation-point flow driven by steady external body force in the form of quadruple vortices. Transition from a steady state to a turbulent state is observed in this flow system, and in the transition path stable periodic motion is found. This periodic motion is characterized in terms of the dynamics of two classes of vortical structures, one of which is the quadruple vortices sustained by the steady body force, and the other is smaller vortex tubes. The smaller tubes are stretched to be intensified in the stagnation-point flow induced by the quadruple vortices. This intesification process is reminiscent of the stretching of smaller vortices between anti-parallel vortices, leading to the energy cascade in isotropic turbulence (Goto 2008,2012).
