A refined derivation of refraction and absorption of the pure O-mode and X-mode Electron Cyclotron Resonance (ECR) wave in tokamak plasma is carried out. The weakly- relativistic dielectric tensor elements are used an...A refined derivation of refraction and absorption of the pure O-mode and X-mode Electron Cyclotron Resonance (ECR) wave in tokamak plasma is carried out. The weakly- relativistic dielectric tensor elements are used and the results show that the refraction only changes a little, compared to that deduced from the cold-plasma dispersion relation even in the inner re- gion. Refined formulae of the wave damping rate are then obtained for both the O-mode and the X-mode fundamental waves.展开更多
A length scale refinement study is a standard practice to ensure the independence of a numerical model on spatial approximations.For smoothed particle hydrodynamics(SPH),the process of length scale refinement study te...A length scale refinement study is a standard practice to ensure the independence of a numerical model on spatial approximations.For smoothed particle hydrodynamics(SPH),the process of length scale refinement study tends to be conducted based on experience.A challenge of defining a universal length scale refinement strategy is the existence of two length scales–particle spacing and smoothing length.Despite the challenge,further investigations of the impact of different refinement strategies should be continually conducted to improve the reliability of practical SPH applications on 3-D free-surface flows.In this study,a conventional strategy and a novel coupled refinement strategy are used to investigate the convergence of SPH simulations for free-surface flows using a standard SPH scheme available in an open-source framework.The two case studies are a dam break flow and a lesser-known stable regime water flow inside a rotating drum with lifters.Validations are conducted using existing data from literature for the dam break flow and laser Doppler velocimetry(LDV)measurements for the rotating drum flow.The investigation shows that the proposed coupled length scale refinement strategy does not offer a significant improvement for the SPH model of the dam break flow comparing with the conventional strategy.On the other hand,the stable regime rotating drum fluid flow shows that both refinement strategies are not sufficient to tackle SPH’s on-going fundamental challenge of accurately predicting the flow field of complex 3-D turbulent flows with free surfaces.展开更多
基金This work is supported by the China Nutional Nature Science Foundation No.19975015
文摘A refined derivation of refraction and absorption of the pure O-mode and X-mode Electron Cyclotron Resonance (ECR) wave in tokamak plasma is carried out. The weakly- relativistic dielectric tensor elements are used and the results show that the refraction only changes a little, compared to that deduced from the cold-plasma dispersion relation even in the inner re- gion. Refined formulae of the wave damping rate are then obtained for both the O-mode and the X-mode fundamental waves.
文摘A length scale refinement study is a standard practice to ensure the independence of a numerical model on spatial approximations.For smoothed particle hydrodynamics(SPH),the process of length scale refinement study tends to be conducted based on experience.A challenge of defining a universal length scale refinement strategy is the existence of two length scales–particle spacing and smoothing length.Despite the challenge,further investigations of the impact of different refinement strategies should be continually conducted to improve the reliability of practical SPH applications on 3-D free-surface flows.In this study,a conventional strategy and a novel coupled refinement strategy are used to investigate the convergence of SPH simulations for free-surface flows using a standard SPH scheme available in an open-source framework.The two case studies are a dam break flow and a lesser-known stable regime water flow inside a rotating drum with lifters.Validations are conducted using existing data from literature for the dam break flow and laser Doppler velocimetry(LDV)measurements for the rotating drum flow.The investigation shows that the proposed coupled length scale refinement strategy does not offer a significant improvement for the SPH model of the dam break flow comparing with the conventional strategy.On the other hand,the stable regime rotating drum fluid flow shows that both refinement strategies are not sufficient to tackle SPH’s on-going fundamental challenge of accurately predicting the flow field of complex 3-D turbulent flows with free surfaces.
