Measurement of the bulk viscosity of liquid by Brillouin scattering.

The aim is to develop a rapid and direct method for measuring the bulk viscosity of a liquid as a function of temperature. Brillouin scattering of a laser beam in fresh water and salt water at different temperatures has been studied. The results show that there exists a close temperature-dependent relationship among the Brillouin frequency shift, the Brillouin linewidth, and the bulk viscosity of water. Thus the bulk viscosity of water can be determined directly from Brillouin-scattering measurements. The method has a high signal-to-noise ratio and high accuracy.