Patent ID: 7007546

Claim:
A method for measuring shear rate at which the viscosity of a fluid is measured utilizing an acoustic wave device, the acoustic wave device having an input and an output transducers, and having a characteristic relationship between input power, output power, and an acoustic wave amplitude at a selected region between the input and output transducer, the acoustic wave device being coupled to the measured fluid, the method comprising the steps of: applying a predetermined power P in of a harmonic signal having a frequency ω to the input transducer, to impart an acoustic wave at the selected region; measuring output power level P out at the output transducer; using the characteristic relationship, and the input and output power levels, calculating the amplitude of the average acoustic wave imparted to the fluid; measuring viscosity of the fluid to obtain a measured viscosity at the selected region; and calculating the shear rate of the fluid at the selected region by using the frequency, the viscosity measurement, and the acoustic wave amplitude.