Possibility of controlled ejection of ferrofluid grains from a magnetically ordered ferrofluid using high frequency non-linear acoustic pulses - a particle dynamical study

We consider a model dilute ferrofluid that is subjected to a strong, homoge neous magnetic field directed perpendicular to the surface of the ferroflui d, such that there is a chain formation in the direction perpendicular to t he surface of the liquid. We study the propagation of impulses generated at high-frequency across finite times through the ferrofluid chains. Our nume rical analysis shows that a very high-frequency sequence of non-linear acou stic pulses of appropriate magnitudes, initiated at the base of the contain er, can lead to the ejection of desired number of ferrofluid grains through the liquid-air interface. The proposed mechanism, if successfully realized in the laboratory, could help design a nozzle-free, ultrafast, ink-jet pri nter of unparalleled resolution. (C) 2000 Elsevier Science B.V. All rights reserved.