Physics-Guided Multiphysics Modeling for Resonance Frequency Identification in Ultrasound Seed Priming.

Introduction: Ultrasound-assisted seed priming is an emerging technology for enhancing germination while reducing water consumption, treatment time, and energy demand. However, the selection of operating frequencies is commonly based on empirical approaches rather than the intrinsic physical properties of seeds. This study presents a physics-guided finite element methodology to identify resonance frequencies and characterize the thermoacoustic response of seeds, providing a scientific basis for the design of efficient ultrasound seed priming systems.

Methods: Three-dimensional finite element models of Lens culinaris (lentil), Raphanus sativus (radish), and Glycine max (soybean) seeds were developed from their characteristic dimensions. The models incorporated the physical properties of each seed, including density, acoustic impedance, sound velocity, thermal conductivity, specific heat capacity, and acoustic absorption coefficient. Coupled Acoustics and Heat Transfer COMSOL Multiphysics modules were employed to simulate acoustic wave propagation through water and its interaction with the seeds. A frequency sweep from 20 to 100 kHz, with 10 Hz increments, was performed to identify resonance frequencies. Additionally, simulations evaluated the influence of different acoustic intensities on the spatial and temporal temperature distributions within the seeds and the surrounding medium.

Results: The simulations identified resonance frequencies of 37 kHz for lentil and soybean seeds, and 24 kHz for radish seeds. In addition, all three species exhibited a pronounced acoustic energy peak near 22 kHz, suggesting a common excitation frequency for multispecies ultrasound treatments. Thermal analyses demonstrated that appropriate selection of acoustic intensity maintains temperatures below 60 °C, reducing the likelihood of thermally induced loss of seed viability while maximizing acoustic energy transfer.

Conclusions: The proposed multiphysics modeling framework provides a physics-based methodology for selecting ultrasound operating conditions and optimizing the design of resource-efficient seed priming technologies. The results support the development of sustainable ultrasound devices capable of improving treatment efficiency while reducing water and energy consumption in agricultural applications.