Modeling the Evaporation and Phase Transition Dynamics of a Single Respiratory Bioaerosol in Air

Respiratory bioaerosol fundamentals are crucial for elucidating the transmission dynamics of infectious diseases. Ambient temperature and humidity fundamentally govern behavior and persistence of respiratory bioaerosols through the modulation of internal solute composition. This study presents a CFD model that tracks the bioaerosol evolution by solving advection-diffusion equations for multicomponent transport and phase transitions. A modified evaporation model accounts for the increasing solute concentration driven by mucin and salt interactions, reducing the water activity and initiating phase transitions. Simultaneously, included proteins undergo aggregation or interfacial adsorption influenced by mucin structure and salt concentration. These changes induce gradients in the momentum equations resolving external convective airflow and internal circulation, which shapes solute transport, coupled via interfacial shear and mass flux continuity. The indicated coupled effects govern whether the single bioaerosol undergoes complete evaporation or stabilizes as a semi-solid residue. These insights support large–scale cloud based simulations and help to predict viral persistence. Therefore, this work supports the development of effective public health strategies to mitigate the spread of airborne transmission.