Forces on micron-sized particles randomly distributed on the surface of larger particles and possibility of detachment
Forces on micron-sized particles randomly distributed on the surface of larger particles and possibility of detachment
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DOI：
10.1016/j.ijmultiphaseflow.2015.01.006
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发表时间：
2015-06-01
影响因子：
3.8
通讯作者：
Sommerfeld, Martin
中科院分区：
文献类型：
--
作者：
Cui, Yan;Sommerfeld, Martin
基于格点-玻尔兹曼方法，对暴露于等速气流中的由大载体颗粒覆盖小球形药物颗粒组成的颗粒团簇进行了数值计算。在这些研究之前，模拟是基于一个测试案例进行验证的，在这个测试案例中，单个颗粒位于平面壁上，暴露在线性剪切流中。仿真结果与分析结果及其它仿真结果进行了比较。此外，在广泛的数值研究基础上，合理选择了所需的小颗粒分辨率和区域尺寸。载体颗粒直径为100 μ m，细颗粒直径分别为3 μ m和5 μ m。所考虑的雷诺数范围在1到200之间。此外，在模拟中，小颗粒对载体的覆盖程度在10%到50%之间变化，并确定了这对分离的影响。从这些模拟中提取了药物颗粒上的流体动力与角度位置的关系，以估计药物颗粒脱离的可能性。脱落可能通过抬升、滑动或滚动发生。发现即使在Re = 200时，由于作用的法向力很小，也不可能升空。基于测量的黏附性能，即范德华力、黏附面能和摩擦系数，估计了与角度位置相关的滑动和滚动分离概率。这些研究的目的是了解药物颗粒脱离载体颗粒在吸入器装置作为建模和优化干粉吸入的基础。(C) 2015 Elsevier Ltd.版权所有。
Numerical calculations based on the Lattice-Boltzmann method were performed for a particle cluster consisting of a large carrier particle covered with small spherical drug particles which were exposed to a constant velocity air flow. Prior to these studies, the simulations were validated based on a test case where a single particle is situated on a plane wall and exposed to a linear shear flow. The present simulations were compared with analytical results and other simulations. Moreover, the required small particle resolution and the domain size were properly selected based on an extensive numerical study. The diameter of the carrier particles was 100 pm, while the fine particles had diameters of 3 mu m and 5 mu m, respectively. The range of Reynolds numbers considered was between 1 and 200. Moreover, the coverage degree of the carrier by the small particles was varied in the simulations between 10% and 50%, and this influence on the detachment was determined. From these simulations the fluid dynamic forces on the drug particles were extracted in dependence of the angular position in order to estimate the possibility of drug particle detachment. Detachment might occur through lift-off, sliding or rolling. Lift-off was found to be not possible due to the acting small normal forces even at Re = 200. The probability of sliding and rolling detachment in dependence of the angular position was estimated based on measured adhesion properties, i.e. van der Waals force, adhesion surface energy and friction coefficient. With these studies it is aimed to understand drug particle detachment from carrier particles in an inhaler device as a basis of modelling and optimising dry powder inhalation. (C) 2015 Elsevier Ltd. All rights reserved.