Influence of acoustic streaming on the stability of an isothermal or laterally heated fluid layer

Influence of acoustic streaming on the stability of an isothermal or laterally heated fluid layer. The linear stability of acoustic streaming flows induced by ultrasound waves (Eckart streaming), for both isothermal and laterally heated fluids confined between two parallel horizontal infinite walls has been studied. The basic profiles were determined analytically, and the eigenvalue problem derived for the temporal stability analysis was solved by a spectral Tau Chebyshev method. In the isothermal case, a critical acoustic parameter A, leading to an oscillatory instability was determined. Ac is minimum for an acoustic beam width (normalized by the height of the fluid layer) H-s = 0.32 and increases when either H-s is decreased or increased. The other result concerns the influence of the acoustic streaming flow on the stability of the laterally heated layer (Hadley flow). For rather small beam widths, the acoustic streaming flow destabilizes the Hadley flow, but for large beam widths (H-s > 0.6), a range of acoustic parameter values was found for which the Hadley flow is stabilized (increase of the thresholds), before a sharp decrease of the thresholds for larger A. Let us underline that the stability of such flows has not been yet studied in the literature. To cite this article: W. Dridi et al., C. R. Mecanique 335 (2007).