Acoustic Streaming Pumps

Martin SE (2001) Parametric analysis of acoustic streaming pumps nfilizing planar ultrasonic acoustic beams. MS thesis, Vandtabilt University... 

Martin SE (2001) Parametric Analysis of Acoustic Streaming Pumps Utilizing Planar Ultrasonic Acoustic Beams. Ms. Thesis, Vanderbilt University... 

Figure 3.51 Pumping with flexural-wave device. Data velocity measured from video recorded motion of polystyrene spheres vs amplitude of wave motion. Solid line theoretical values based on acoustic streaming theory. (Reprimed with permission. See Ref. [74). 1989...

An approximate analysis of FPW fluid pumping [74,75,78] indicates that acoustic streaming accounts well for the observed pumping speeds observed in the experiments with water and the marker spheres. The transport of granular particles is believed to result from pumping of the ambient air. In addition, the FPW wave intensity and relatively low frequency favor the production of sono-chemical effects [79]. 

Acoustic Streaming, Fig. 7 Effect of the channel depth on the flow rate at three Reynolds numbers for the flexural-plate-wave pumping. Dashed line corresponds to Re = oo... 

Thus, to analyze acoustic streaming, one must first solve the equations of linear acoustics to obtain the first-order fields. This is followed by the calculation of the effective body foree (41) and the solution of the Stokes equation (40) for the time-averaged streaming flow, driven by the effective force. Guttenberg et al. [7] have carried out such an analysis to investigate pumping in a capillary gap driven by SAW. 

Ultrasonic pumps are pumps that use acoustic streaming to create a fluid motion inside microchannels. Acoustic streaming is the time-averaged flow induced hy an ultrasonic wave (periodic pressure oscillation). Attenuation of the acoustic energy (via reflection and other distortion) generates a body force within the fluid and converts acoustic energy into kinetic energy of the fluid [1]. 

Ultrasonic pumps are very useful for microscale applications due to their simphcity, robustness and scaling advantages. Moreover, they are insensitive to the chemical state of the fluid and the waU material unlike electroosmotic and magnetic pumps. By using acoustic streaming as a pumping mechanism, noncontact fluid control is achievable since no contact is needed between the acoustic source and the fluid and no valves are required [2]. 

A somewhat indirect method for measuring characteristic impedance at low frequencies is used in the acoustic streaming device of Thurston, in which the liquid is pumped back and forth through parallel capillaries. It is appropriate for liquids of very low viscosity in a continuous frequency range from 10 to 300 Hz. 

Du XY, Swan wick ME, Fu YQ, Luo JK, Hewitt AJ, Lee DS, Maeng S, Milne WI (2009) Surface acoustic wave induced streaming and pumping in for microfluidic applications. J Micromech Microeng 19 035016... 

---