A fully coupled thermo-hygro-mechanical Multiphysics model for simulating microwave heating and dehydration of porous materials

Microwave heating is a rapid and efficient method for processing porous materials like food, but it is often plagued by non-uniform heating and unpredictable textural changes. The simulation of microwave heating in porous materials requires a careful choice of model complexity to balance predictive accuracy with computational cost. While fully coupled models are available, the relative importance of each physical coupling is not always clear. This study utilizes a comprehensive thermo-hygro-mechanical model to systematically investigate the role of thermal, hydraulic, and mechanical phenomena during microwave dehydration. Our results reveal a critical feedback loop where hygric contraction significantly alters the material’s geometry, creating a geometric focusing effect on the electromagnetic field that is absent in uncoupled models. By analyzing simulations with varying degrees of physical coupling, this work provides a guideline for researchers to determine when a fully coupled approach is necessary, thereby facilitating more targeted and efficient model development for designing real-world microwave drying experiments.