Ultrasonic wave propagation in particle compounded gels

Attenuation and sound velocity in particle compounded agar were measured by an ultrasonic wave transmission technique at frequencies ranging from 1 MHz to 8 MHz. The observed values were discussed using Urick's theory for viscous suspensions. The measured values of attenuation and sound velocity were in good agreement with the calculated values using Urick's theory up to a particle concentration of 10%. This means that Urick's theory can be applied not only to suspensions, but also to particle compounded gels. Furthermore, from the investigation of the experimental results obtained using this theory, it was clarified that the attenuation depends on the particle density. In particular, it should be noted that n depends on the particle diameter (the attenuation α can be expressed with the equation α = α0fn, where α0 and n are constants and f is frequency). All measured and calculated results suggested that the acoustic properties in these kinds of particle compounded gels could be estimated theoretically.