Frequency dependent structures in an electrostatically driven powder medium

Effect of grain size on the forces governing the dynamic behavior of electrostatically driven powder media

“…approximately 1 mm in diameter will suffer the mechanical effects of forces and torques when subjected to electric fields, and closely spaced particles often exhibit strong mutual interactions, cohesion, chaining, and fingering, and therefore, structure and pattern recognitions can be achieved in different liquid or air media [1][2][3][4][5][6][7][8][9][10][11].…”

“…In a previous article [1], we experimentally studied microsized granular media (with grain sizes from 1 to 130 μm) under an ac uniform electric field, and the phase in which there is no movement in the powder was called "precipitated granular solid phase" or Phase I (PI). This regime will extend from 6 zero amplitude of the applied voltage up to a threshold value beyond which the particles start to move.…”

“…[1], both dynamic regimes were experimentally 59 studied, and a diagram was constructed (based on the ex-60 perimental data obtained in Ref. [1]) showing the voltage 61 amplitude-frequency space regions in which either construc-62 tive or destructive behavior was experimentally observed. 63 Figure 1 shows the diagram and some representative pictures 64 of the observed behavior.…”

“…Within this dynamic 7 66 regime, in Ref. [1], we distinguished three different qualitative 67 zones where each one develops a singular morphology and 68 dynamics: high frequency zone (HFZ), medium frequency 69 zone (MFZ), and low frequency zone (LFZ), respectively. In 70 Phase III (PIII), a completely destructive behavior is observed 71 where individual movements cause instabilities that prevent 72 the growth and cohesion of grains and cause a granular gas.…”

“…In Ref. [1], the boundaries between phases were determined 74 by visual inspection of the video records performed during the 75 experiments. In each experiment, the voltage is increased from 76 zero at constant rate and frequency, according to the protocol 77 also used in the present article.…”