Thermoacoustic Sensing of Temperature Variations in Water-Saturated Porous Media.

Accurate monitoring of temperature variations in fluid flow through porous media is important for numerous geophysical, environmental, and chemical processes. Traditional temperature measurement techniques often suffer from limitations such as invasiveness, restricted spatial coverage, or limited capability for real-time subsurface sensing. Thermoacoustic (TA) methods provide a promising alternative by combining electromagnetic excitation with acoustic detection to enable non-contact subsurface monitoring. In this work, thermoacoustic measurements were conducted over a temperature range of 20-60 °C using a water-saturated sand porous medium, and a multiphysics simulation framework incorporating rock physics models, temperature-dependent material properties, acoustic dispersion, and attenuation calibration was developed to reproduce the experimental observations. A clear relationship between temperature and TA signal amplitude was observed, and strong agreement was achieved between the experimentally measured and simulated thermoacoustic responses after applying the proposed calibration procedures. The results demonstrate the feasibility of using thermoacoustic signals to monitor bulk temperature variations in porous media and establish a foundation for future development of spatially resolved thermoacoustic temperature imaging methods.