论文标题
有限大小的球体在湍流中的动力学:流量结构和粒子边界层的作用
Dynamics of finite-size spheroids in turbulent flow: the roles of flow structures and particle boundary layers
论文作者
论文摘要
我们通过完全分辨的数值模拟研究中性合构大小的球体的平移和旋转动力学。我们检查轴对称形状,从扁平到碎裂,颗粒体积的依赖性。我们表明,非球体惯性尺度颗粒所经历的加速度和旋转是由于体积过滤的流体力和扭矩,类似于球形颗粒。然而,粒子取向带有与周围流量结构的优先对齐的签名,这反映在不同的轴向和侧向波动中,以使其加速和旋转速率。即使对于惯性范围内的体积等效尺寸的粒子,方向的随机化也不会发生,此处最高为60美元$η$ at $re_λ= 120 $。此外,我们证明了粒子周围流体边界层的作用不能被忽略以对粒子统计动力学的定量理解,因为它们会影响角速度的强度,以及相对于旋转旋转的相对重要性。这项研究使惯性尺度的流动结构在均质和各向同性湍流中的重要性及其对中性构建体的运输的影响,其大小在惯性范围内。
We study the translational and rotational dynamics of neutrally-buoyant finite-size spheroids in hydrodynamic turbulence by means of fully resolved numerical simulations. We examine axisymmetric shapes, from oblate to prolate, and the particle volume dependences. We show that the accelerations and rotations experienced by non-spherical inertial-scale particles result from volume filtered fluid forces and torques, similar to spherical particles. However, the particle orientations carry signatures of preferential alignments with the surrounding flow structures, which is reflected in distinct axial and lateral fluctuations for accelerations and rotation rates. The randomization of orientations does not occur even for particles with volume equivalent diameter size in the inertial range, here up to 60 $η$ at $Re_λ=120$. Additionally, we demonstrate that the role of fluid boundary layers around the particles cannot be neglected to reach a quantitative understanding of particle statistical dynamics, as they affect the intensities of angular velocities, and the relative importance of tumbling with respect to spinning rotations. This study brings to the fore the importance of inertial-scale flow structures in homogeneous and isotropic turbulence and their impacts on the transport of neutrally-buoyant bodies with size in the inertial range.