| |

The Effect of Sound on Viscoelastic Properties of Oils | |

Many inhomogeneous liquids reveal the property of viscosity variation under shear stress, displaying at the same time viscoelastic behavior. The viscosity of these so called non-Newtonian liquids usually decreases with increase in the shear stress and as a result the medium slips along a smooth surface. Crude oil is proved to be a real non-Newtonian liquid. Two examples of experimental investigation of sound effect on the oil shear viscosity are considered in the paper. The first one shows a new nonlinear acoustics process in a confined Non-newtonian liquid - stimulated acoustical transparency of oil in a thin capillary as a waveguide, and the second one demonstrates the effect of acoustical liquefaction of frozen crude oil in a pipe. Effects under discussion may belong to a wide class of instabilities arising in dynamical systems, and be interpreted similarly to the models of the earthquake fault dynamics. |