Simulation of Fluid Dynamics Monitoring Using Ultrasonic Measurements

International audienceThe simulation of the propagation of ultrasonic waves in a moving fluid will improve theefficiency of the ultrasonic flow monitoring and that of the in-service monitoring for various reactorsin several industries. The most recent simulations are mostly limited to 3D representations of theinsonified volume but without really considering the temporal aspect of the flow. The advent of highperformancecomputing (HPC) now makes it possible to propose the first 4D simulations, with therepresentation of the inspected medium evolving over time. This work is based on a highly accuratedouble simulation. A first computational fluid dynamics (CFD) simulation, performed in previouswork, described the fluid medium resulting from the mixing of hot jets in a cold opaque fluid. Therehave been many sensor developments over the years in this domain, as ultrasounds are the onlymethod able to give information in an opaque medium. The correct design of these sensors, as wellas the precise and confident analysis of their measurements, will progress with the development ofthe modeling of wave propagation in such a medium. An important parameter to consider is theflow temperature description, as a temperature gradient in the medium deflects the wave path andmay sometimes cause its division. We develop a 4D wave propagation simulation in a very realistic,temporally fluctuating medium. A high-performance simulation is proposed in this work to includean ultrasonic source within the medium and to calculate the wave propagation between a transmitterand a receiver. The analysis of the wave variations shows that this through-transmission setup cantrack the jet mixing time variations. The steps needed to achieve these results are described using thespectral-element-based numerical tool SPECFEM3D. It is shown that the low-frequency fluctuationof the liquid metal flow can be observed using ultrasonic measurements