Measuring Newtonian viscosity from the phase of reflected ultrasonic shearwave

In this paper, an acoustic shear impedance model is employed to obtain a re lation between the viscosity of a Newtonian fluid and phase characteristics of ultrasonic shear wave reflection from a solid-fluid interface. The phas e and magnitude of the reflection coefficient can be decoupled in this mode l. The decoupling allows an independent relation between the acoustic shear impedance (viscosity-density product) and phase of the reflection coeffici ent. The model was experimentally verified for different fluid-solid combin ations. Comparison of the results with the commonly used absolute reflectio n coefficient method demonstrates that phase measurement provides improved measurements. (C) 2000 Published by Elsevier Science B.V. All rights reserv ed.