Analysis on Secondary Flow Characteristics inside Bronchia of NonHeart Beating Donor Lung
1 Institute of Biothermal Science and Technology, University of Shanghai for Science and Technology, Shanghai 200093, China
2 Institute of Refrigeration and Cryogenic Engineering, University of Shanghai for Science and Technology， Shanghai 200093,China
3 Shanghai Pulmonary Hospital, Shanghai 200433,China
Abstract：Nonheart beating donor (NHBD) lung is expected to be the most potential donor source for clinical lung transplantation, and low temperature ventilation was normally thought to effectively protect the donor lung in vivo. A 3D asymmetric bronchial model with four levels was reconstructed, and computational fluid dynamics (CFD) technique was adopted here for investigating the sencond flow structures inside NHBD lung bronchia under three kind respiratory frequencies, i.e. 0.125 Hz,0.25 Hz and 0.5 Hz. The results show that no second flow structures exist inside main bronchia during inspiration process, and the maximum difference of dimensionless velocity across the main section is 0.67@0.125 Hz, 0.5@0.25 Hz and 0.3 @0.5 Hz, respectively. However, there are obvious differences for the expiration process, and the maximum difference of dimensionless velocity across the main section is 1.25, 1.1 and 1.06, respectively. Due to the asymmetric structure of bronchial and bifurcation rotation angles, the second flow structures always present for further daughter bronchias but the maximum difference of dimensionless velocity of them do not change significantly with increasing breathing rates (about 1.0). Generally, the flow structures inside left side are more complicated than the right side. The current work indicates that the second flow structures always exist when low temperature ventilation is utilized to pretect NHBD lung, which may be beneficial to develop the optimization method for preserving NHBD lung in situ.
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