Maity Priyanka
Institute of Thermodynamics and Fluid Mechanics, Technische Universität Ilmenau, Postfach 100565, D-98684 Ilmenau, Germany.
Phys Rev E. 2023 Jun;107(6-2):065107. doi: 10.1103/PhysRevE.107.065107.
We revisit the problem of heavy particles suspended in homogeneous box turbulence flow subjected to rotation along the vertical axis, which introduces anisotropy along the vertical and horizontal planes. We investigate the effects of the emergent structures due to rotation, on the spatial distribution and temporal statistics of the particles. The distribution of particles in the flow are studied using the joint probability distribution function (JPDFs) of the second and third principle invariants of the velocity gradient tensor, Q and R. At high rotation rates, the JPDFs of Lagrangian Q-R plots show remarkable deviations from the well-known teardrop shape. The cumulative probability distribution functions for times during which a particle remains in vortical or straining regions show exponentially decaying tails except for the deviations at the highest rotation rate. The average residence times of the particles in vortical and straining regions are also affected considerably due to the addition of rotation. Furthermore, we compute the temporal velocity autocorrelation and connect it to the Lagrangian anisotropy in presence of rotation. The spatial and temporal statistics of the particles are determined by a complex competition between the rotation rate and inertia of the particle.
我们重新审视了悬浮在沿垂直轴旋转的均匀箱式湍流中的重粒子问题,这种旋转会在垂直和水平平面上引入各向异性。我们研究了由旋转产生的结构对粒子空间分布和时间统计的影响。利用速度梯度张量的第二和第三主不变量Q和R的联合概率分布函数(JPDFs)研究了流场中粒子的分布。在高旋转速率下,拉格朗日Q - R图的JPDFs显示出与著名的泪滴形状有显著偏差。粒子停留在涡旋或应变区域的时间的累积概率分布函数除了在最高旋转速率下有偏差外,显示出指数衰减的尾部。由于旋转的加入,粒子在涡旋和应变区域的平均停留时间也受到显著影响。此外,我们计算了时间速度自相关,并将其与存在旋转时的拉格朗日各向异性联系起来。粒子的空间和时间统计由旋转速率和粒子惯性之间的复杂竞争决定。