2019 年 19 巻 2 号 p. 137-144
Flow structure in human bronchus is experimentally investigated. Resin bronchus model that is made by 3D printer is provided for the experiment. Velocity distributions are measured by PIV. Microbubble is used as tracer particle of the PIV measurement. Refractive index matching technique are applied to measure velocity in the bronchus model. To simulate non-uniform inlet flow from larynx including Dean vortices, a bent pipe is connected upstream of the bronchus model. Dean number was changed by the radius of curvature of the bent pipe. Due to this inlet condition, velocity distribution in the bronchus model shows distorted top-hat profile. In branch region and curved region of the bronchus model, velocity distributions that indicate adverse pressure gradient condition are confirmed. Separated flows are also confirmed in those region. Dean vortices induced from upstream bent pipe uniformize velocity distribution in the bronchus model. Strong Dean vortices may restrict flow separation in the adverse pressure gradient region. This trend is remarkably observed in higher Dean number condition.