Vortex methods have been alternative tools of finite element and finite difference methods for several decades. This paper presents a brief review of vortex method development in the last decades and introduces effici...Vortex methods have been alternative tools of finite element and finite difference methods for several decades. This paper presents a brief review of vortex method development in the last decades and introduces efficient vortex methods developed for high Reynolds number bluff body flows and suitable for running on parallel computer architectures. Included in this study are particle strength exchange methods, core-spreading method, deterministic particle method and hybrid vortex methods. Combined with conservative methods, vortex methods can comprise the most available tools for simulations of three-dimensional complex bluff body flows at high Reynolds numbers.展开更多
The flow of pseudoplastic power-law fluids with different flow indexes at a microchannel plate was studied using computational fluid dynamic simulation.The velocity distribution along the microchannel plate and especi...The flow of pseudoplastic power-law fluids with different flow indexes at a microchannel plate was studied using computational fluid dynamic simulation.The velocity distribution along the microchannel plate and especially in the microchannel slits,flow pattern along the outlet arc and the pressure drop through the whole of microchannel plate were investigated at different power-law flow indexes.The results showed that the velocity profile in the microchannel slits for low flow index fluids was similar to the plug flow and had uniform pattern.Also the power-law fluids with lower flow indexes had lower stagnation zones near the outlet of the microchannel plate.The pressure drop through the microchannel plate showed huge differences between the fluids.The most interesting result was that the pressure drops for power-law fluids were very smaller than that of Newtonian fluids.In addition,the heat transfer of the fluids through the microchannel with different channel numbers in a wide range of Reynolds number was investigated.For power-law fluid with flow index(n=0.4),the Nusselt number increases continuously as the number of channels increases.The results highlight the potential use of using pseudoplastic fluids in the microheat exchangers which can lower the pressure drop and increase the heat transfer efficiency.展开更多
When workflow task needs several datasets from different locations m cloud, data transfer becomes a challenge. To avoid the unnecessary data transfer, a graphical-based data placement algo- rithm for cloud workflow is...When workflow task needs several datasets from different locations m cloud, data transfer becomes a challenge. To avoid the unnecessary data transfer, a graphical-based data placement algo- rithm for cloud workflow is proposed. The algorithm uses affinity graph to group datasets while keeping a polynomial time complexity. By integrating the algorithm, the workflow engine can intelligently select locations in which the data will reside to avoid the unnecessary data transfer during the initial stage and runtime stage. Simulations show that the proposed algorithm can effectively reduce data transfer during the workflow＇ s execution.展开更多
The hydrodynamic behavior in a high-density downer reactor was studied. A two-fluid model based on the kinetic theory of granular flow with a k-ε turbulent model was developed to simulate the flow behavior in the sys...The hydrodynamic behavior in a high-density downer reactor was studied. A two-fluid model based on the kinetic theory of granular flow with a k-ε turbulent model was developed to simulate the flow behavior in the system. This simulation achieved an averaged solid fraction in the bed as high as 18% in this operating regime. The flow development in high-density downer consists of 3 regions, which are first acceleration, second acceleration, and fully developed regions. In the fully developed region, the lateral distribution of the solid volume fraction is low and almost uniform in the center region with a high density peak near the wall region. Gas and solid velocities gradually increase toward the wall and form a peak near the wall region. In addition, the solid volume fraction, gas and solid velocities increase with solid circulation rate.展开更多
基金Project (No. 50236030) supported by the National Natural Science Foundation of China
文摘Vortex methods have been alternative tools of finite element and finite difference methods for several decades. This paper presents a brief review of vortex method development in the last decades and introduces efficient vortex methods developed for high Reynolds number bluff body flows and suitable for running on parallel computer architectures. Included in this study are particle strength exchange methods, core-spreading method, deterministic particle method and hybrid vortex methods. Combined with conservative methods, vortex methods can comprise the most available tools for simulations of three-dimensional complex bluff body flows at high Reynolds numbers.
文摘The flow of pseudoplastic power-law fluids with different flow indexes at a microchannel plate was studied using computational fluid dynamic simulation.The velocity distribution along the microchannel plate and especially in the microchannel slits,flow pattern along the outlet arc and the pressure drop through the whole of microchannel plate were investigated at different power-law flow indexes.The results showed that the velocity profile in the microchannel slits for low flow index fluids was similar to the plug flow and had uniform pattern.Also the power-law fluids with lower flow indexes had lower stagnation zones near the outlet of the microchannel plate.The pressure drop through the microchannel plate showed huge differences between the fluids.The most interesting result was that the pressure drops for power-law fluids were very smaller than that of Newtonian fluids.In addition,the heat transfer of the fluids through the microchannel with different channel numbers in a wide range of Reynolds number was investigated.For power-law fluid with flow index(n=0.4),the Nusselt number increases continuously as the number of channels increases.The results highlight the potential use of using pseudoplastic fluids in the microheat exchangers which can lower the pressure drop and increase the heat transfer efficiency.
基金Supported by the National Natural Science Foundation of China(No.60903137,60970132)
文摘When workflow task needs several datasets from different locations m cloud, data transfer becomes a challenge. To avoid the unnecessary data transfer, a graphical-based data placement algo- rithm for cloud workflow is proposed. The algorithm uses affinity graph to group datasets while keeping a polynomial time complexity. By integrating the algorithm, the workflow engine can intelligently select locations in which the data will reside to avoid the unnecessary data transfer during the initial stage and runtime stage. Simulations show that the proposed algorithm can effectively reduce data transfer during the workflow＇ s execution.
文摘The hydrodynamic behavior in a high-density downer reactor was studied. A two-fluid model based on the kinetic theory of granular flow with a k-ε turbulent model was developed to simulate the flow behavior in the system. This simulation achieved an averaged solid fraction in the bed as high as 18% in this operating regime. The flow development in high-density downer consists of 3 regions, which are first acceleration, second acceleration, and fully developed regions. In the fully developed region, the lateral distribution of the solid volume fraction is low and almost uniform in the center region with a high density peak near the wall region. Gas and solid velocities gradually increase toward the wall and form a peak near the wall region. In addition, the solid volume fraction, gas and solid velocities increase with solid circulation rate.
