Capturing both carrier and disperse phases in dense suspensions using harmonic ultrasound imaging velocimetry

Abstract

In this study, a new ultrasound-based method for measuring both carrier-fluid and suspended-particle (disperse phase) motion is introduced. The method can extract flow quantities, such as slip velocity, from statistical information obtained in dense two-phase flows. The carrier fluid velocity is measured by leveraging the non-reflective properties of nearly-linear materials at harmonic frequencies to filter out the suspended particles. In contrast, the disperse phase velocity is measured using the ultrasound’s fundamental imaging mode and the slight impedance mismatch between the suspended particles and fluid. As a result, the carrier phase can be captured without cross-talk from the disperse phase. Finally, it is shown that the proposed technique allows for the measurement of suspension dynamics in vortex rings with high volume fractions on the order of 40%. Here, the proposed method is tested in dense suspensions, made from super-absorbent polymer beads with nearly-linear material properties mixed in deionized water, with volume fractions ranging from 20% to 40%.