Department of Physics, Technical University of Denmark, DTU Physics Building 309, DK-2800 Kongens Lyngby, Denmark.
Department of Biomedical Engineering, Lund University, Ole Römers väg 3, 22363, Lund, Sweden.
Phys Rev Lett. 2023 Jan 27;130(4):044001. doi: 10.1103/PhysRevLett.130.044001.
Acoustic streaming at high acoustic energy densities E_{ac} is studied in a microfluidic channel. It is demonstrated theoretically, numerically, and experimentally with good agreement that frictional heating can alter the streaming pattern qualitatively at high E_{ac} above 400 J/m^{3}. The study shows how as a function of increasing E_{ac} at fixed frequency, the traditional boundary-driven four streaming rolls created at a half-wave standing-wave resonance transition into two large streaming rolls. This nonlinear transition occurs because friction heats up the fluid resulting in a temperature gradient, which spawns an acoustic body force in the bulk that drives thermoacoustic streaming.
在高声能密度 E_{ac}下研究了微流道中的声流。理论、数值和实验结果表明，在高于 400 J/m^{3}的高 E_{ac}下，摩擦加热可以定性地改变流动模式。该研究展示了随着 E_{ac}的增加（固定频率），在半波驻波共振处产生的传统边界驱动的四个流辊如何转变为两个大的流辊。这种非线性转变是因为摩擦会使流体升温，从而产生温度梯度，这会在体中产生声体力，从而驱动热声流。
