ABSTRACT
Objective Based on computational fluid dynamics (CFD) method, the air and aerosol transport in a single alveolus were simulated to study the characteristics of airflow and aerosol transport in deep alveolus. Methods A long straight duct with a hemispherical wall at one end which had periodic expansion/contraction were regarded as simplified approximation of a single alveolus. Based on this, a two-dimensional (2D) mathematical model was established.The Euler-Euler method was used to solve the transport equations of airflow and aerosol particles in the alveolus considering air diffusion along the hemisphere boundary. Results The composition ratio of the air in the duct changed in a stable periodic way during the whole breathing process.The aerosol transport in the duct mainly depended on the particle diffusion coefficient. The advection transport had only a small effect on it. The diffusion velocity and depth of aerosol increased when the particle size decreased, especially when the particle size was smaller than 4 μm. The increase of respiratory frequency and amplitude could significantly improved the transport capacity of aerosol particles. Conclusions In atomization treatment, aerosol particles with smaller particle size have better transportation and curative efficacy. Deep breathing should be encouraged to improve particle transport.
ABSTRACT
Objective To research a fast method on establishment of simplified model of the spine.Methods The 3D geometry of the spine is reconstructed using a multiview radiography reconstruction technique through the two plane X-rays by extracting the spinal anatomy information combined with the statistical geometrical information.Results The entire spine finite element modeling including the thoracic spine(T1-T12),lumbar spine(L1-L5) and the sacrum was reconstructed,and the analysis proved that lateral corrective force can correct scoliosis to a certain extent.Conclusion Because the method needs less time,and causes less radiation to patients,it can be brought much convenience and support to the clinical application.