A total variation diminishing-weighted average flux （TVD-WAF）-based hybrid numerical scheme for the enhanced version of nonlinearly dispersive Boussinesq-type equations was developed. The one-dimensional governing e...A total variation diminishing-weighted average flux （TVD-WAF）-based hybrid numerical scheme for the enhanced version of nonlinearly dispersive Boussinesq-type equations was developed. The one-dimensional governing equations were rewritten in the conservative form and then discretized on a uniform grid. The finite volume method was used to discretize the flux term while the remaining terms were approximated with the finite difference method. The second-order TVD-WAF method was employed in conjunction with the Harten-Lax-van Leer （HLL） Riemann solver to calculate the numerical flux, and the variables at the cell interface for the local Riemann problem were reconstructed via the fourth- order monotone upstream-centered scheme for conservation laws （MUSCL）. The time marching scheme based on the third-order TVD Runge- Kutta method was used to obtain numerical solutions. The model was validated through a series of numerical tests, in which wave breaking and a moving shoreline were treated. The good agreement between the computed results, documented analytical solutions, and experimental data demonstrates the correct discretization of the governing equations and high accuracy of the proposed scheme, and also conforms the advantages of the proposed shock-capturing scheme for the enhanced version of the Boussinesq model, including the convenience in the treatment of wave breaking and moving shorelines and without the need for a numerical filter.展开更多
Ion temperature gradient(ITG)-driven turbulence with embedded static magnetic islands is simulated by utilizing a gyrokinetic theory-based global turbulence transport code(GKNET)in this work.Different from the traditi...Ion temperature gradient(ITG)-driven turbulence with embedded static magnetic islands is simulated by utilizing a gyrokinetic theory-based global turbulence transport code(GKNET)in this work.Different from the traditional equilibrium circular magnetic-surface average(EMSA)method,an advanced algorithm that calculates the perturbed magnetic-surface average(PMSA)of the electric potential has been developed to precisely deal with the zonal flow component in a non-circular magnetic surface perturbed by magnetic islands.Simulations show that the electric potential vortex structure inside islands induced by the magnetic islands is usually of odd parity when using the EMSA method.It is found that the odd symmetry vortex can transfer into an even one after a steep zonal flow gradient,i.e.the flow shear has been built in the vicinity of the magnetic islands by adopting the PMSA algorithm.The phase of the potential vortex in the poloidal cross section is coupled with the zonal flow shear.Such an electric potential vortex mode may be of essential importance in wide topics,such as the turbulence spreading across magnetic islands,neoclassical tearing mode physics,and also the interaction dynamics between the micro-turbulence and MHD activities.展开更多
In this paper,Eliassen-Palm theory and associated diagnostic method are used to discuss the dynamical mechanism of the interaction between eddy flux and zonal averaged flow in the sudden change of the general circulat...In this paper,Eliassen-Palm theory and associated diagnostic method are used to discuss the dynamical mechanism of the interaction between eddy flux and zonal averaged flow in the sudden change of the general circulation in the Northern Hemisphere in early summer of 1982,which indicates that the northward jump of subtropic jet stream is closely related to the enhanced transport of mid-latitude eddy energy to the subtropic tro- popause.However,the direction of the transport is conditioned by the structure of zonal averaged flow.It is evident that the adjustment of zonal averaged flow responses quickly to the eddy transport during this episode. As regard to the suddenness of the change of circulation,the critical role is played by the eddy forcing,展开更多
Latent heat storage plays an important role in the utilization of solar energy.However,the low thermal conductivity of phase change materials(PCM)significantly reduces the heat transfer efficiency of latent heat stora...Latent heat storage plays an important role in the utilization of solar energy.However,the low thermal conductivity of phase change materials(PCM)significantly reduces the heat transfer efficiency of latent heat storage systems.To enhance its storage/release efficiency,optimizing the fin geometry is essential.This paper establishes a validated three-dimensional numerical model that considers PCM natural convection to study the effects of fin height and number on the heat transfer process.The fin volume of all models is kept constant,and the fin height is determined by the annular space.The impact of fin heights(0.3ΔR,0.5ΔR,0.7ΔR,0.9ΔR)and numbers(4,8,10,16)on heat transfer efficiency was investigated by analyzing the PCM temperature distribution on the shell section,the liquid fraction within the shell over time,and the average heat transfer rate and heat flux.The results show that increasing the fin height from 0.3ΔR to 0.9ΔR reduces the heat storage and release completion times by 61.16%and 45.43%,respectively.Similarly,increasing the number of fins from 4 to 16 reduces the heat storage and release completion times by 33.35%and 31.13%,respectively.The study concludes that increasing both the fin number and height dilutes the heat flux between the fin and PCM during both the heat storage and release processes,with the fin number having a more significant effect on reducing heat flux than fin height.Therefore,when the fin volume remains constant,increasing fin height is more conducive to improving the heat transfer performance of the PCM.These findings will provide a foundation for the application of finned tube energy storage systems in building energy conservation and other fields.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51579034)the Open Fund of the Key Laboratory of Ocean Circulation and Waves,Chinese Academy of Sciences(Grant No.KLOCW1502)
文摘A total variation diminishing-weighted average flux （TVD-WAF）-based hybrid numerical scheme for the enhanced version of nonlinearly dispersive Boussinesq-type equations was developed. The one-dimensional governing equations were rewritten in the conservative form and then discretized on a uniform grid. The finite volume method was used to discretize the flux term while the remaining terms were approximated with the finite difference method. The second-order TVD-WAF method was employed in conjunction with the Harten-Lax-van Leer （HLL） Riemann solver to calculate the numerical flux, and the variables at the cell interface for the local Riemann problem were reconstructed via the fourth- order monotone upstream-centered scheme for conservation laws （MUSCL）. The time marching scheme based on the third-order TVD Runge- Kutta method was used to obtain numerical solutions. The model was validated through a series of numerical tests, in which wave breaking and a moving shoreline were treated. The good agreement between the computed results, documented analytical solutions, and experimental data demonstrates the correct discretization of the governing equations and high accuracy of the proposed scheme, and also conforms the advantages of the proposed shock-capturing scheme for the enhanced version of the Boussinesq model, including the convenience in the treatment of wave breaking and moving shorelines and without the need for a numerical filter.
基金partially supported by the National Key R&D Program of China(No.2019YFE0300002)by National Natural Science Foundation of China(Nos.U1967206 and 12275071)。
文摘Ion temperature gradient(ITG)-driven turbulence with embedded static magnetic islands is simulated by utilizing a gyrokinetic theory-based global turbulence transport code(GKNET)in this work.Different from the traditional equilibrium circular magnetic-surface average(EMSA)method,an advanced algorithm that calculates the perturbed magnetic-surface average(PMSA)of the electric potential has been developed to precisely deal with the zonal flow component in a non-circular magnetic surface perturbed by magnetic islands.Simulations show that the electric potential vortex structure inside islands induced by the magnetic islands is usually of odd parity when using the EMSA method.It is found that the odd symmetry vortex can transfer into an even one after a steep zonal flow gradient,i.e.the flow shear has been built in the vicinity of the magnetic islands by adopting the PMSA algorithm.The phase of the potential vortex in the poloidal cross section is coupled with the zonal flow shear.Such an electric potential vortex mode may be of essential importance in wide topics,such as the turbulence spreading across magnetic islands,neoclassical tearing mode physics,and also the interaction dynamics between the micro-turbulence and MHD activities.
文摘In this paper,Eliassen-Palm theory and associated diagnostic method are used to discuss the dynamical mechanism of the interaction between eddy flux and zonal averaged flow in the sudden change of the general circulation in the Northern Hemisphere in early summer of 1982,which indicates that the northward jump of subtropic jet stream is closely related to the enhanced transport of mid-latitude eddy energy to the subtropic tro- popause.However,the direction of the transport is conditioned by the structure of zonal averaged flow.It is evident that the adjustment of zonal averaged flow responses quickly to the eddy transport during this episode. As regard to the suddenness of the change of circulation,the critical role is played by the eddy forcing,
基金Natural Scientific Research Project of Hunan Province(No's.2022JJ31046 and 2023JJ50027).
文摘Latent heat storage plays an important role in the utilization of solar energy.However,the low thermal conductivity of phase change materials(PCM)significantly reduces the heat transfer efficiency of latent heat storage systems.To enhance its storage/release efficiency,optimizing the fin geometry is essential.This paper establishes a validated three-dimensional numerical model that considers PCM natural convection to study the effects of fin height and number on the heat transfer process.The fin volume of all models is kept constant,and the fin height is determined by the annular space.The impact of fin heights(0.3ΔR,0.5ΔR,0.7ΔR,0.9ΔR)and numbers(4,8,10,16)on heat transfer efficiency was investigated by analyzing the PCM temperature distribution on the shell section,the liquid fraction within the shell over time,and the average heat transfer rate and heat flux.The results show that increasing the fin height from 0.3ΔR to 0.9ΔR reduces the heat storage and release completion times by 61.16%and 45.43%,respectively.Similarly,increasing the number of fins from 4 to 16 reduces the heat storage and release completion times by 33.35%and 31.13%,respectively.The study concludes that increasing both the fin number and height dilutes the heat flux between the fin and PCM during both the heat storage and release processes,with the fin number having a more significant effect on reducing heat flux than fin height.Therefore,when the fin volume remains constant,increasing fin height is more conducive to improving the heat transfer performance of the PCM.These findings will provide a foundation for the application of finned tube energy storage systems in building energy conservation and other fields.
