Observation of von Karman vortex street in a droplet breakup

We report the first observation of von Karman vortex street in a droplet breakup induced by shock waves and high-speed fluid after the shock. To obtain these data, a novel experimental system is used to record the interaction between the droplet and shock wave and the following fluid. Details of flow fields and transients are also presented and discussed. Based on high-speed shadowgraphs, a Strouhal number of 0.28 +/- 0.09 with a Reynolds number of 2817 is obtained, which is in good qualitative agreement with earlier experiments on the von Karman vortex street. The results suggest that the vortex-induced vibration may dominate the oscillation in the horizontal direction, which would result in resonance when the frequency of the oscillating flow matches the natural frequency of the droplet, thereby enhancing the deformation and breakup of the droplet. Our data may be useful to benchmark related multiphase flow models or nonlinear theories.

Automated summary

The experiment observed the von Karman vortex street in a droplet breakup induced by shock waves and high-speed fluid, recorded the interaction between the droplet and shock wave, and obtained details of flow fields and transients. The results suggest that vortex-induced vibration may dominate the oscillation in the horizontal direction, enhancing the deformation and breakup of the droplet when the oscillating flow frequency matches the droplet's natural frequency. The data may be useful for benchmarking related multiphase flow models or nonlinear theories.