The influence of inlet velocity profile on three-dimensional three-generation bifurcating flows

 The influence of inlet velocity profile on the three-dimensional three-generation bifurcating flow has been numerically studied using a CFD code based on finite volume method. The bifurcating airways simulated the branches of human lung. The axial length and cross-sectional diameter of the three-generation airway are taken from the anatomic data of the 5th–7th generation airway of an averaged height man. The curvature and bifurcating angle of each junction are taken as 2.265 diameter of the next generation and 70∘, respectively, from physiological consideration. Computations are carried out for eight Reynolds numbers ranging from 200 to 1600, each under uniform and parabolic inlet velocity profiles, to consider the relations between the entry flow patterns and the overall flow characteristics including mainstream flow pattern, secondary flow vortices, asymmetrical flow partition and pressure drop. The mass flow ratio between the medial and lateral branch, and the total pressure drop are closely related to the entry flow patterns for larger Reynolds numbers.