This paper presents a comparative study of a meshless level-set method in the simulation of sloshing flows. The numerical moving particle semi-implicit （MPS） method and a grid based schemes of the MPS and level-set ...This paper presents a comparative study of a meshless level-set method in the simulation of sloshing flows. The numerical moving particle semi-implicit （MPS） method and a grid based schemes of the MPS and level-set methods are outlined and two violent sloshing cases are considered. The computed results are compared with the corresponding experimental data for validation. The impact pressure and the deformations of free surface induced by sloshing are comparatively analyzed, and are in good agreement with experimental ones. Results show that both the MPS and level-set methods are good tools for simulation of violent sloshing flows. However, the second pressure peaks as well as breaking and splashing of free surface by the MPS method are captured better than by the level-set method.展开更多
In the process of deep projects excavation,deep rock often experiences a full stress process from high stress to unloading and then to impact disturbance failure.To study the dynamic characteristics of three-dimension...In the process of deep projects excavation,deep rock often experiences a full stress process from high stress to unloading and then to impact disturbance failure.To study the dynamic characteristics of three-dimensional high stressed red sandstone subjected to unloading and impact loads,impact compression tests were conducted on red sandstone under confining pressure unloading conditions using a modified split Hopkinson pressure bar.Impact disturbance tests of uniaxial pre-stressed rock were also conducted(without considering confining pressure unloading effect).The results demonstrate that the impact compression strength of red sandstone shows an obvious strain rate effect.With an approximately equal strain rate,the dynamic strength of red sandstone under confining unloading conditions is less than that in the uniaxial pre-stressed impact compression test.Confining pressure unloading produces a strength-weakening effect,and the dynamic strength weakening factor(DSWF)is also defined.The results also indicate that the strain rate of the rock and the incident energy change in a logarithmic relation.With similar incident energies,unloading results in a higher strain rate in pre-stressed rock.According to the experimental analysis,unloading does not affect the failure mode,but reduces the dynamic strength of pre-stressed rock.The influence of confining pressure unloading on the shear strength parameters(cohesion and friction angle)is discussed.Under the same external energy impact compression,prestressed rock subjected to unloading is more likely to be destroyed.Thus,the effect of unloading on the rock mechanical characteristics should be considered in deep rock project excavation design.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.51379125,51411130131 and 11272120)the National Key Basic Research Development of China(973 Program,Grant No.2013CB036103)+1 种基金the High Te-chnology of Marine Research Project of the Ministry of Indu-stry and the Information Technology of Chinathe Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning(Grant No.2013022)
文摘This paper presents a comparative study of a meshless level-set method in the simulation of sloshing flows. The numerical moving particle semi-implicit （MPS） method and a grid based schemes of the MPS and level-set methods are outlined and two violent sloshing cases are considered. The computed results are compared with the corresponding experimental data for validation. The impact pressure and the deformations of free surface induced by sloshing are comparatively analyzed, and are in good agreement with experimental ones. Results show that both the MPS and level-set methods are good tools for simulation of violent sloshing flows. However, the second pressure peaks as well as breaking and splashing of free surface by the MPS method are captured better than by the level-set method.
基金Projects(42077244,41877272)supported by the National Natural Science Foundation of ChinaProject(2020-05)supported by the Open Research Fund of Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization,China。
文摘In the process of deep projects excavation,deep rock often experiences a full stress process from high stress to unloading and then to impact disturbance failure.To study the dynamic characteristics of three-dimensional high stressed red sandstone subjected to unloading and impact loads,impact compression tests were conducted on red sandstone under confining pressure unloading conditions using a modified split Hopkinson pressure bar.Impact disturbance tests of uniaxial pre-stressed rock were also conducted(without considering confining pressure unloading effect).The results demonstrate that the impact compression strength of red sandstone shows an obvious strain rate effect.With an approximately equal strain rate,the dynamic strength of red sandstone under confining unloading conditions is less than that in the uniaxial pre-stressed impact compression test.Confining pressure unloading produces a strength-weakening effect,and the dynamic strength weakening factor(DSWF)is also defined.The results also indicate that the strain rate of the rock and the incident energy change in a logarithmic relation.With similar incident energies,unloading results in a higher strain rate in pre-stressed rock.According to the experimental analysis,unloading does not affect the failure mode,but reduces the dynamic strength of pre-stressed rock.The influence of confining pressure unloading on the shear strength parameters(cohesion and friction angle)is discussed.Under the same external energy impact compression,prestressed rock subjected to unloading is more likely to be destroyed.Thus,the effect of unloading on the rock mechanical characteristics should be considered in deep rock project excavation design.
