论文标题
在轴对称停滞点流中中性合并的球形粒子上的近壁力
Near-wall forces on a neutrally-buoyant spherical particle in an axisymmetric stagnation-point flow
论文作者
论文摘要
基于适当的形式的相互定理，预测作用于浸入壁构成的轴对称停滞点流（HIEMENZ-HOMANN流）的中性构型球形颗粒（HIEMENZ-HOMANN流）的水动力力。建立了不受干扰的速度场的近似代数形式，模仿了整个边界层的实际载流流的逐渐过渡，从散装中的纯线性拉紧流程到壁上的抛物线流动。假定粒子雷诺数是较小的，并且首先基于基于蠕变流的假设进行预测。然后，假设粒子足够接近壁，以使后者处于干扰的内部区域，则计算惯性校正。以微分方程的形式获得了粒子和环境流体之间时间相关的滑动速度的预测，首先假设粒子沿流动对称轴移动，然后将分析扩展到在任意径向位置释放的粒子。在前一种情况下，将这些预测与数值模拟提供的结果进行了比较。当基于应变的雷诺数（建立在粒子半径上，大容量中的应变速率）超过$ 0.1 $时，由于颗粒壁相互作用以及粒子和流体之间的相对加速度引起的有限惯性效应可实质性地修改了滑动速度与距离距离距离的方式。
Hydrodynamic forces acting on a neutrally-buoyant spherical particle immersed in a wall-bounded axisymmetric stagnation point flow (Hiemenz-Homann flow) are predicted, based on a suitable form of the reciprocal theorem. An approximate algebraic form of the undisturbed velocity field is set up, mimicking the gradual transition of the actual carrying flow throughout the boundary layer, from a pure linear straining flow in the bulk to a parabolic flow at the wall. The particle Reynolds number is assumed to be small and predictions based on the creeping-flow assumption are first derived. Then, inertial corrections are computed, assuming that the particle stands close enough to the wall for the latter to be in the inner region of the disturbance. Predictions for the time-dependent slip velocity between the particle and ambient fluid are obtained in the form of a differential equation, first assuming that the particle moves along the flow symmetry axis, then extending the analysis to particles released at an arbitrary radial position. In the former case, these predictions are compared with results provided by numerical simulations. When the strain-based Reynolds number (built on the particle radius and strain rate in the bulk) exceeds $0.1$, finite-inertia effects due to particle-wall interactions and to the relative acceleration between the particle and fluid are found to substantially modify the way the slip velocity varies with the distance to the wall.
