We investigate the effect of particle shape on the transportation mechanism in well-drilling using a three-dimensional model that couples computational fluid dynamics （CFD） with the discrete element method （DEM）. ...We investigate the effect of particle shape on the transportation mechanism in well-drilling using a three-dimensional model that couples computational fluid dynamics （CFD） with the discrete element method （DEM）. This numerical method allows us to incorporate the fluid-particle interactions （drag force, contact force, Saffman lift force, Magnus lift force, buoyancy force） using momentum exchange and the non-Newtonian behavior of the fluid. The interactions of particle-particle, particle-wall, and particle-drill pipe are taken into account with the Hertz-Mindlin model. We compare the transport of spheres with non-spherical particles （non-smooth sphere, disc, and cubic） constructed via the multi- sphere method for a range of fluid inlet velocities and drill pipe inclination angles. The simulations are carried out for laboratory-scale drilling configurations. Our results demonstrate good agreement with published experimental data. We evaluate the fluid-particle flow patterns, the particle velocities, and the particle concentration profiles. The results reveal that particle sphericity plays a major role in the fluid-solid interaction. The traditional assumption of an ideal spherical particle may cause inaccurate results.展开更多
基于分区交错算法,通过对商业流体软件Fluent和结构计算软件Ansys的二次开发,搭建了高层建筑风振数值模拟平台。耦合界面上非匹配网格的搜索配对和数据传递,以及流体域的网格更新均采用UDF(User Defined Functions)编程实现;流体计算采...基于分区交错算法,通过对商业流体软件Fluent和结构计算软件Ansys的二次开发,搭建了高层建筑风振数值模拟平台。耦合界面上非匹配网格的搜索配对和数据传递,以及流体域的网格更新均采用UDF(User Defined Functions)编程实现;流体计算采用大涡模拟方法配合使用流体并行计算技术,以兼顾计算效率和精度,通过UDF和Scheme语言编程实现流体域参数化求解,为确保流体和结构域时间步长一致,流体计算采用子迭代技术;结构计算采用APDL(Ansys Parametric Design Language)语言参数化编程;采用Visual C++语言编制数值模拟平台主进程实现模块间的相互调用。采用该方法,对大气紊流边界层风场内方形截面高层建筑的风振气弹响应进行了数值模拟,将计算结果与气弹模型风洞试验和文献数值模拟结果进行了对比;还通过有、无考虑气动弹性时结构位移响应的比较,分析了气动阻尼对结构风振响应的影响。结果表明,该数值模拟方法可以较精确地求解高层建筑结构的风振气弹响应问题。展开更多
文摘We investigate the effect of particle shape on the transportation mechanism in well-drilling using a three-dimensional model that couples computational fluid dynamics （CFD） with the discrete element method （DEM）. This numerical method allows us to incorporate the fluid-particle interactions （drag force, contact force, Saffman lift force, Magnus lift force, buoyancy force） using momentum exchange and the non-Newtonian behavior of the fluid. The interactions of particle-particle, particle-wall, and particle-drill pipe are taken into account with the Hertz-Mindlin model. We compare the transport of spheres with non-spherical particles （non-smooth sphere, disc, and cubic） constructed via the multi- sphere method for a range of fluid inlet velocities and drill pipe inclination angles. The simulations are carried out for laboratory-scale drilling configurations. Our results demonstrate good agreement with published experimental data. We evaluate the fluid-particle flow patterns, the particle velocities, and the particle concentration profiles. The results reveal that particle sphericity plays a major role in the fluid-solid interaction. The traditional assumption of an ideal spherical particle may cause inaccurate results.
