流固耦合作用下真实人体上呼吸道气溶胶扩散沉积的仿真与实验

摘要

The diffusion and deposition of aerosol in human upper respiratory tract was simulated by using the large eddy simulation method and Lagrangian stochastic trajectory model with 3D standardized model of realistic human upper respiratory tract under the fluid-solid interaction and cyclic respiratory pattern.The influence of vortex evolution on the diffusion of aerosol was analyzed and the deposition fraction of aerosol in human upper respiratory tract was measured,which verified that the numerical simulation method was accurate and reasonable.The results showed that the aerosol particles with size of 0.3 μm were more likely to pass through the upper respiratory tract and move into the lower bronchus than the particles with size of 6.5 μm in the phase of inhalation.The aerosol particles entering into the upper tract by the exhalation flow returned,convoluted or deposited in the tract and some of the aerosol particles were taken out of mouth during the exhalation.The deposition fraction of the aerosol particles with sizes of 0.3 μm and 6.5 μm was high in throat and trachea,and low in the mouth.The deposition fraction of the aerosol particles with size of 6.5 μm in different zones of the upper respiratory tract was obviously higher than that with size of 0.3 μm.With the fluid-solid interaction,the deposition fraction of aerosol particles decreased due to the airflow impact cushioning caused by the deformation of respiratory tract.The mechanism of deposition for the larger aerosol particles was inertial impaction,and the deposition for the smaller aerosol particles was more likely to be affected by the turbulent dispersion and entrainment of eddy current.%通过构建真实人体上呼吸道三维规范模型,运用大涡模拟数值方法和Lagrangian随机轨道模型,对考虑流固耦合作用时循环呼吸模式下上呼吸道内气溶胶的扩散沉积进行数值仿真,分析气流涡结构演化对气溶胶扩散的影响,并通过实验对气溶胶在人体上呼吸道的沉积率进行测量,验证仿真方法的正确性.结果表明:循环吸气时,0.3μm气溶胶颗粒比6.5 μm气溶胶颗粒更容易通过上呼吸道而进入更深层次的支气管;循环呼气时,部分进入上呼吸道的颗粒在呼出气流夹带下,在气道中折返、回旋、沉积,而有些则从口腔中呼出;0.3和6.5μm气溶胶颗粒在咽、喉以及气管内沉积较多,而在口腔内沉积较少;6.5μm气溶胶颗粒在上呼吸道不同部位的沉积率明显高于0.3 μm气溶胶;流固耦合作用时咽部、喉部的壁面形变可缓冲气流冲击,气溶胶颗粒在咽喉部位的沉积率有所下降;大粒径气溶胶颗粒沉积受惯性碰撞影响较大,而小粒径气溶胶颗粒沉积受湍流扩散及涡流夹带的影响较大.