Acoustic Localization and Communication for Lagrangian Sensor Particles

• Applicant: Professor Dr.-Ing. Christian Kupsch
• Subject Area: Measurement Systems ; Fluid Mechanics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 571041517

The simultaneous investigation of three-dimensional fluid flows and the corresponding fields of physical or chemical fluid properties is of central importance for the understanding and optimization of numerous technical processes. Conventional measurement techniques are often limited by the geometric and physical boundary conditions of the experimental setup, restricting measurements to predefined, fixed positions. A promising approach to overcome these limitations is the use of Lagrangian Sensor Particles (LSPs), which move passively with the flow while continuously measuring fluid and flow properties throughout the entire fluid volume. However, the application of this technology is currently constrained by methodological limitations related to localization and data transmission. In particular, there is a lack of reliable methods to assign the measured data to specific positions in space, which prevents the reconstruction of the fields of fluid and flow properties. The objective of this project is to investigate and advance acoustic methods for localization and data transmission for LSPs in relevant fluid environments—with the long-term goal of significantly extending the capabilities of this technology. The central concept involves implementing LSPs as acoustic beacons that periodically emit signals. By measuring the signal arrival times at multiple external receivers, the spatial position of each LSP within the fluid volume can be determined. Using multiplexing techniques, the method can be extended to allow the simultaneous localization of multiple LSPs. Additionally, sensor data can be encoded within the acoustic signals, thereby enabling their transmission from the LSP to the outside of the fluid. As a result, the acquired sensor data can be linked to a specific measurement location. Furthermore, by tracking the position of an LSP over time, the flow field can be estimated. The measured flow and fluid properties can be used for real-time monitoring and control of processes. The proposed research raises several fundamental scientific questions: • How can acoustic channels for data transmission and localization be modeled considering the fluid properties? • What modifications are necessary to adapt existing localization techniques from airborne acoustics to fluid environments? • How can robust data transmission be achieved concurrently with accurate localization? • How do fluid properties and flow conditions influence signal quality and localization accuracy? • What uncertainties arise in the simultaneous localization of multiple particles, and how can they be quantified and minimized? Answering these questions will establish a fundamental understanding of acoustic localization and communication in fluids in the context of LSPs.

• DFG Programme: Research Grants