Kijanski Nadine, Krach David, Steeb Holger
Institute of Applied Mechanics (CE), University of Stuttgart, Pfaffenwaldring 7, 70569 Stuttgart, Germany.
Stuttgart Center for Simulation Technology, Pfaffenwaldring 5a, 70569 Stuttgart, Germany.
Materials (Basel). 2020 May 19;13(10):2324. doi: 10.3390/ma13102324.
Solid particles immersed in a fluid can be found in many engineering, environmental or medical fields. Applications are suspensions, sedimentation processes or procedural processes in the production of medication, food or construction materials. While homogenized behavior of these applications is well understood, contributions in the field of pore-scale fully resolved numerical simulations with non-spherical particles are rare. Using Smoothed Particle Hydrodynamics (SPH) as a simulation framework, we therefore present a modeling approach for Direct Numerical Simulations (DNS) of single-phase fluid containing non-spherically formed solid aggregates. Notable and discussed model specifications are the surface-coupled fluid-solid interaction forces as well as the contact forces between solid aggregates. The focus of this contribution is the numerical modeling approach and its implementation in SPH. Since SPH presents a fully resolved approach, the construction of arbitrary shaped particles is conveniently realizable. After validating our model for single non-spherical particles, we therefore investigate the motion of solid bodies in a Newtonian fluid and their interaction with the surrounding fluid and with other solid bodies by analyzing velocity fields of shear flow with respect to hydromechanical and contact forces. Results show a dependency of the motion and interaction of solid particles on their form and orientation. While spherical particles move to the centerline region, ellipsoidal particles move and rotate due to vortex formation in the fluid flow in between.
沉浸在流体中的固体颗粒在许多工程、环境或医学领域都能见到。其应用包括悬浮液、沉降过程，以及药物、食品或建筑材料生产中的程序过程。虽然这些应用的均匀化行为已得到充分理解，但在孔隙尺度上对非球形颗粒进行完全解析的数值模拟领域的研究却很少。因此，我们以光滑粒子流体动力学（SPH）作为模拟框架，提出一种对包含非球形固体聚集体的单相流体进行直接数值模拟（DNS）的建模方法。值得注意且将进行讨论的模型规范是表面耦合的流固相互作用力以及固体聚集体之间的接触力。本论文的重点是数值建模方法及其在SPH中的实现。由于SPH提供了一种完全解析的方法，方便实现任意形状颗粒的构建。在验证了我们针对单个非球形颗粒的模型后，我们通过分析剪切流相对于流体力学和接触力的速度场，研究了固体在牛顿流体中的运动及其与周围流体以及其他固体的相互作用。结果表明，固体颗粒的运动和相互作用取决于它们的形状和取向。球形颗粒会向中心线区域移动，而椭圆形颗粒由于其间流体流动中形成的涡旋而移动并旋转。
