Numerical Study to Determine Water-Air Dispersion with Ultrasound Waves

The König-project is funded by the German state with the aim to develop a calibrated and virtual measurement laboratory to enhance methods based on ultrasound measurements that find application in the determination of flow velocity or particle movement. By comparing the results of controlled laboratory and real-world experiments with numerical simulations, the understanding of the interaction between ultrasonic waves and fluid flow is intended to be improved. The amount of scatterers within a fractured medium directly affects  the effective velocity of elastic waves. Thus we investigate, if the effects found in solid media can be transferred to fluids. We ran a series of numerical experiments, simulating ultrasound transmission measurements for multiple concentrations of bubbles of varying diameter dissolved in a stationary water layer. For the simulation of elastic wave propagation, we used a rotated staggered finite-difference scheme. We investigate the relation between the effective wave speed and the bubble concentration and compare those to results of laboratory experiments. Future research will then expand to moving fluid-gas mixtures.