Doinikov Alexander A, Thibault Pierre, Marmottant Philippe
LIPhy UMR 5588, CNRS/Université Grenoble-Alpes, Grenoble F-38401, France.
LIPhy UMR 5588, CNRS/Université Grenoble-Alpes, Grenoble F-38401, France.
Ultrasonics. 2018 Jul;87:7-19. doi: 10.1016/j.ultras.2018.02.002. Epub 2018 Feb 5.
A mathematical model is derived for acoustic streaming in a microfluidic channel confined between a solid wall and a rigid reflector. Acoustic streaming is produced by two orthogonal ultrasound standing waves of the same frequency that are created by two pairs of counter-propagating leaky surface waves induced in the solid wall. The magnitudes and phases of the standing waves are assumed to be different. Full analytical solutions are found for the equations of acoustic streaming. The obtained solutions are used in numerical simulations to reveal the structure of the acoustic streaming. It is shown that the interaction of two standing waves leads to the appearance of a cross term in the equations of acoustic streaming. If the phase lag between the standing waves is nonzero, the cross term brings about circular vortices with rotation axes perpendicular to the solid wall of the channel. The vortices make fluid particles rotate and move alternately up and down between the solid wall and the reflector. The obtained results are of immediate interest for acoustomicrofluidic applications such as the ultrasonic micromixing of fluids and the manipulation of microparticles.
推导了一个数学模型，用于描述在固体壁和刚性反射器之间的微流体通道中的声流。声流由频率相同的两个正交超声驻波产生，这两个驻波由固体壁中两对反向传播的泄漏表面波产生。假设驻波的幅度和相位不同。找到了声流方程的完整解析解。将得到的解用于数值模拟，以揭示声流的结构。结果表明，两个驻波的相互作用导致声流方程中出现交叉项。如果驻波之间的相位滞后不为零，交叉项会产生旋转轴垂直于通道固体壁的圆形涡旋。这些涡旋使流体颗粒旋转，并在固体壁和反射器之间交替上下移动。所获得的结果对于诸如流体的超声微混合和微粒操纵等声微流体应用具有直接的意义。
