VISCOUS MECHANISM IN THE THEORY OF ULTRASOUND ATTENUATION ANISOTROPY BY MAGNETIC FLUIDS

Abstract

We report a comparative analysis of the classical theory of the viscous mechanism of sound attenuation by ultrafine media and one of the dominant theories of sound attenuation anisotropy by magnetic fluids on the basis of the viscous mechanism. The Taketomi theory used by many authors gives overestimated values for the size of aggregates in magnetic fluids and is not able to quantify experimental data. In addition, the formula obtained by Taketomi does not reduce to the classical expression for viscous absorption in the limiting case and, therefore, should be considered erroneous.

Keywords

• magnetic fluids
• attenuation coefficient
• anisotropy
• aggregates
• viscous mechanism