Vibrofluidic motion of individual granules

Application of a horizontal, dual mode vibratory waveform has been shown to induce net motion for macroscopic objects, provided that the waveform is non-antiperiodic. Here we present detailed experimental measurements of how the vibratory amplitude, frequency, and phase lag affect the motion of individual granules and larger objects. We show that the net velocity depends strongly on the relative amplitude and phase lag of the second frequency mode. At very large vibratory amplitudes or frequencies, we observe that the velocity is insensitive to the frictional coefficients. We demonstrate that this behavior is consistent with an asymptotic analysis based on a frictional Froude number, and we discuss the implications for control of granular fluids.