Influence of viscoelasticity on ultrasonic propagation in poly(ethylene oxide) aqueous solution

Abstract

Generally, ultrasonic propagation in ultrasonic non-destructive testing is regarded as a linear process, during which the interaction between ultrasonic and measured material is rarely considered. In this study, the mechanisms of ultrasonic propagation in viscoelastic poly(ethylene oxide) aqueous solution and the interaction between ultrasound and fluid are investigated. A theoretical model of ultrasonic propagation in a viscoelastic fluid is established, in which the body force from ultrasonic waves is added to the fluid momentum equation, and the viscoelasticity of the fluid is described by the Oldroyd-B model. The simulation results for the ultrasonic reflection coefficient at the solid–liquid boundary and the attenuation coefficient based on the multi-physics coupling method are experimentally verified. The results of this study show that the ultrasonic absorption coefficient at low frequencies from 2.25 to 7.5 MHz exhibits frequency dependence through ultrasonic relaxation spectroscopy. The simulation results of the velocity of disturbed flow during ultrasonic propagation show that the viscosity of the solution has a greater impact on the disturbance than the relaxation time, and the phase angle difference between the stress and strain also shows that the viscosity is the main factor affecting the ultrasonic propagation.