Regurgitation in the heart diastolic phase represents a critical flow condition associated with many heart valve design considerations. The finite volume method, the Low-Reynolds-Number k-ω turbulent model and slidin...Regurgitation in the heart diastolic phase represents a critical flow condition associated with many heart valve design considerations. The finite volume method, the Low-Reynolds-Number k-ω turbulent model and sliding mesh model are employed to solve and compare the complex flow field and the torque in each case. The end results expected from a cardiovascular CFD analysis are not limited only to the flowfield investigations. More importantly, it needs an evaluation criterion to judge if the design is acceptable as considered from a broader blood cell damage or activation perspective. In this study, blood cell damage index developed based on stress-time empirical rule and Lagrangian particle tracking is introduced to assess the viscous and turbulence-induced stresses effect to the blood cells.展开更多
A slowdown of sea surface height （SSH） rise occurred in the Nordic （GIN） seas around 2004. In this study, SSH satellite data and constructed steric height data for the decades before and after 2004 （i.e., May 199...A slowdown of sea surface height （SSH） rise occurred in the Nordic （GIN） seas around 2004. In this study, SSH satellite data and constructed steric height data for the decades before and after 2004 （i.e., May 1994 to April 2014） were used for comparative analysis. The findings indicate that the rate of slowdown of SSH rises in the GIN seas （3.0 mm/a） far exceeded that of the global mean （0.6 mm/a）. In particular, the mean steric height of the GIN seas increased at a rate of 4.5 mm/a and then decreased at a slower pace. This was the main factor responsible for the stagnation of the SSH rises, while the mass factor only increased slightly. The Norwegian Sea particularly experienced the most prominent slowdown in SSH rises, mainly due to decreased warming of the 0-600 m layer. The controlling factors of this decreased warming were cessation in the increase of volume of the Atlantic inflow and stagnation of warming of the inflow. However, variations in air-sea thermal flux were not a major factor. In the recent two decades, mean halosteric components of the GIN seas decreased steadily and remained at a rate of 2 mm/a or more because of increased flow and salinity of the Atlantic inflow during the first decade, and reduction in freshwater inputs from the Arctic Ocean in the second decade.展开更多
文摘Regurgitation in the heart diastolic phase represents a critical flow condition associated with many heart valve design considerations. The finite volume method, the Low-Reynolds-Number k-ω turbulent model and sliding mesh model are employed to solve and compare the complex flow field and the torque in each case. The end results expected from a cardiovascular CFD analysis are not limited only to the flowfield investigations. More importantly, it needs an evaluation criterion to judge if the design is acceptable as considered from a broader blood cell damage or activation perspective. In this study, blood cell damage index developed based on stress-time empirical rule and Lagrangian particle tracking is introduced to assess the viscous and turbulence-induced stresses effect to the blood cells.
基金The National Natural Science Foundation of China under contract No.41330960the National Major Scientific Research Program on Global Changes under contract No.2015CB953900
文摘A slowdown of sea surface height （SSH） rise occurred in the Nordic （GIN） seas around 2004. In this study, SSH satellite data and constructed steric height data for the decades before and after 2004 （i.e., May 1994 to April 2014） were used for comparative analysis. The findings indicate that the rate of slowdown of SSH rises in the GIN seas （3.0 mm/a） far exceeded that of the global mean （0.6 mm/a）. In particular, the mean steric height of the GIN seas increased at a rate of 4.5 mm/a and then decreased at a slower pace. This was the main factor responsible for the stagnation of the SSH rises, while the mass factor only increased slightly. The Norwegian Sea particularly experienced the most prominent slowdown in SSH rises, mainly due to decreased warming of the 0-600 m layer. The controlling factors of this decreased warming were cessation in the increase of volume of the Atlantic inflow and stagnation of warming of the inflow. However, variations in air-sea thermal flux were not a major factor. In the recent two decades, mean halosteric components of the GIN seas decreased steadily and remained at a rate of 2 mm/a or more because of increased flow and salinity of the Atlantic inflow during the first decade, and reduction in freshwater inputs from the Arctic Ocean in the second decade.
