Ejection of ferrofluid grains using nonlinear acoustic impulses - A particle dynamical study

We consider a model dilute ferrofluid with the grains suspended in water (e .g., gamma-Fe2O3) and subject the system to a strong, homogeneous magnetic field directed perpendicular to the surface such that there is chain format ion along the field direction. We show that an appropriate impulse initiate d at the base of the container might travel as a nondispersive soliton puls e with sufficient energy to overcome surface tension and eject the ferroflu id grain nearest to the liquid-air interface. The proposed mechanism, if su ccessfully realized in the laboratory, could help design a nozzle-free, ink -jet printer of unparalleled resolution. (C) 1999 American Institute of Phy sics. [S0003-6951(99)03436-1].