Smoothed particle hydrodynamics（SPH） method with numerical diffusive terms shows satisfactory stability and accuracy in some violent fluid–solid interaction problems. However, in most simulations, uniform particle ...Smoothed particle hydrodynamics（SPH） method with numerical diffusive terms shows satisfactory stability and accuracy in some violent fluid–solid interaction problems. However, in most simulations, uniform particle distributions are used and the multi-resolution, which can obviously improve the local accuracy and the overall computational efficiency, has seldom been applied. In this paper, a dynamic particle splitting method is applied and it allows for the simulation of both hydrostatic and hydrodynamic problems. The splitting algorithm is that, when a coarse（mother） particle enters the splitting region, it will be split into four daughter particles, which inherit the physical parameters of the mother particle. In the particle splitting process,conservations of mass, momentum and energy are ensured. Based on the error analysis, the splitting technique is designed to allow the optimal accuracy at the interface between the coarse and refined particles and this is particularly important in the simulation of hydrostatic cases. Finally, the scheme is validated by five basic cases, which demonstrate that the present SPH model with a particle splitting technique is of high accuracy and efficiency and is capable for the simulation of a wide range of hydrodynamic problems.Smoothed particle hydrodynamics（SPH）method with numerical diffusive terms shows satisfactory stability and accuracy in some violent fluid–solid interaction problems.However,in most simulations,uniform particle distributions are used and the multi-resolution,which can obviously improve the local accuracy and the overall computational efficiency,has seldom been applied.In this paper,a dynamic particle splitting method is applied and it allows for the simulation of both hydrostatic and hydrodynamic problems.The splitting algorithm is that,when a coarse（mother）particle enters the splitting region,it will be split into four daughter particles,which inherit the physical parameters of the mother particle.In the particle splitting process,conservations of mass,momentum and energy are ensured.Based on the error analysis,the splitting technique is designed to allow the optimal accuracy at the interface between the coarse and refined particles and this is particularly important in the simulation of hydrostatic cases.Finally,the scheme is validated by five basic cases,which demonstrate that the present SPH model with a particle splitting technique is of high accuracy and efficiency and is capable for the simulation of a wide range of hydrodynamic problems.展开更多
The present paper reports the rapid surface alloying induced by the bombardment of high-current pulsed electron beam. Two kinds of substrate materials were examined to show this effect. The first sample was a pure Al ...The present paper reports the rapid surface alloying induced by the bombardment of high-current pulsed electron beam. Two kinds of substrate materials were examined to show this effect. The first sample was a pure Al metal pre-coated with fine carbon powders prior to the bombardment, and the second alloy is the D2-Crl2MolVl mould steel pre-coated with Cr, Ti, and TiN powders. The surface elements diffuse about several micrometers into the substrate materials only after several bombardments. Tribological behaviors of these samples were characterized and significant improvement in wear resistance was found. Finally, a TEM analysis reveals the presence of stress waves generated by coupled thermal and stress fields, which was considered as the main cause of the enhanced properties.展开更多
基金supported by the National Natural Science Foundation of China (Grant 51609049)the Science Foundation of Heilongjiang Province (Grant QC2016061)the Fundamental Research Funds for the Central Universities (Grants HEUGIP201701,HEUCFJ170109)
文摘Smoothed particle hydrodynamics（SPH） method with numerical diffusive terms shows satisfactory stability and accuracy in some violent fluid–solid interaction problems. However, in most simulations, uniform particle distributions are used and the multi-resolution, which can obviously improve the local accuracy and the overall computational efficiency, has seldom been applied. In this paper, a dynamic particle splitting method is applied and it allows for the simulation of both hydrostatic and hydrodynamic problems. The splitting algorithm is that, when a coarse（mother） particle enters the splitting region, it will be split into four daughter particles, which inherit the physical parameters of the mother particle. In the particle splitting process,conservations of mass, momentum and energy are ensured. Based on the error analysis, the splitting technique is designed to allow the optimal accuracy at the interface between the coarse and refined particles and this is particularly important in the simulation of hydrostatic cases. Finally, the scheme is validated by five basic cases, which demonstrate that the present SPH model with a particle splitting technique is of high accuracy and efficiency and is capable for the simulation of a wide range of hydrodynamic problems.Smoothed particle hydrodynamics（SPH）method with numerical diffusive terms shows satisfactory stability and accuracy in some violent fluid–solid interaction problems.However,in most simulations,uniform particle distributions are used and the multi-resolution,which can obviously improve the local accuracy and the overall computational efficiency,has seldom been applied.In this paper,a dynamic particle splitting method is applied and it allows for the simulation of both hydrostatic and hydrodynamic problems.The splitting algorithm is that,when a coarse（mother）particle enters the splitting region,it will be split into four daughter particles,which inherit the physical parameters of the mother particle.In the particle splitting process,conservations of mass,momentum and energy are ensured.Based on the error analysis,the splitting technique is designed to allow the optimal accuracy at the interface between the coarse and refined particles and this is particularly important in the simulation of hydrostatic cases.Finally,the scheme is validated by five basic cases,which demonstrate that the present SPH model with a particle splitting technique is of high accuracy and efficiency and is capable for the simulation of a wide range of hydrodynamic problems.
文摘The present paper reports the rapid surface alloying induced by the bombardment of high-current pulsed electron beam. Two kinds of substrate materials were examined to show this effect. The first sample was a pure Al metal pre-coated with fine carbon powders prior to the bombardment, and the second alloy is the D2-Crl2MolVl mould steel pre-coated with Cr, Ti, and TiN powders. The surface elements diffuse about several micrometers into the substrate materials only after several bombardments. Tribological behaviors of these samples were characterized and significant improvement in wear resistance was found. Finally, a TEM analysis reveals the presence of stress waves generated by coupled thermal and stress fields, which was considered as the main cause of the enhanced properties.
