Wave turbulence transition in Dust Acoustic Wave

Weng-Ji Chen^1*, Po-Cheng Lin¹, Lin I¹

¹Department of Physics, National Central University, Jhongli, Taiwan

* Presenter:Weng-Ji Chen, email:aw538736810@yahoo.com.tw

In hydrodynamic flows, such as channel, pipe and Taylor-Couette flows, the local disordered flow fields are identified as turbulent puffs, which decay, intermittently emerge and spread in spatiotemporal domain on the way to turbulent transition. In this work, the phase transition from stable plane wave to wave turbulence through intermediate weakly disordered wave is investigated in self-excited dust acoustic waves, composed of negatively charged particles suspended in low pressure RF discharges. Through direct observing dust density fluctuations over a large area, we demonstrate the extraction of local turbulent regions (LTRs) associated with incoherent multi-mode excitation in spatiotemporal domains, from the background of plane wave in the weakly disordered state by calculating instantaneous frequency bandwidth with wavelet transform. LTRs with high frequency bandwidth are found intermittently emerging in stable background to rapid spreading with increasing volume fraction in the process of turbulent transition.

Keywords: Dust acoustic wave , wave turbulence , turbulent transition , turbulent puff