  The aerosol formation is associated with the rupture of the liquid plug
during the pulmonary airway reopening. The fluid dynamics of this process is
difficult to predict because the rupture involved complex liquid-gas
transition. Equation of state (EOS) plays a key role in the thermodynamic
process of liquid-gas transition. Here, we propose an EOS-based multiphase
lattice Boltzmann model, in which the nonideal force is directly evaluated by
EOSs. This multiphase model is used to model the pulmonary airway reopening and
study aerosol formation during exhalation. The numerical model is first
validated with the simulations of Fujioka et al.(2008). and the result is in
reasonable agreement with their study. Furthermore, two rupture cases with and
without aerosol formation are contrasted and analyzed. It is found that the
injury on the epithelium in the case with aerosol formation is essentially the
same that of without aerosol formation even while the pressure drop in airway
increases by about 67%. Then extensive simulations are performed to investigate
the effects of pressure drop, thickness of liquid plug and film on aerosol size
and the mechanical stresses. The results show that aerosol size and the
mechanical stresses increase as the pressure drop enlarges and thickness of
liquid plug become thicken, while aerosol size and the mechanical stresses
decrease as thickness of liquid film is thicken. The present multiphase model
can be extended to study the generation and transmission of bioaerosols which
can carry the bioparticles of influenza or coronavirus.
