Fully resolved numerical simulations of a micron-sized spherical particles residing on a surface with large-scale roughness are performed by using the Lattice–Boltzmann method. The aim is to investigate the influence of surface roughness on the detachment of fine drug particles from larger carrier particles for transporting fine drug particles in a DPI (dry powder inhaler). Often the carrier surface is modified by mechanical treatments for modifying the surface roughness in order to reduce the adhesion force of drug particles. Therefore, drug particle removal from the carrier surface is equivalent to the detachment of a sphere from a rough plane surface. Here a sphere with a diameter of 5 μm at a particle Reynolds number of 1.0, 3.5 and 10 are considered. The surface roughness is described as regularly spaced semi-cylindrical asperities (with the axes oriented normal to the flow direction) on a smooth surface. The influence of asperity distance and size ratio (i.e. the radius of the semi-cylinder to the particle radius, R_c/R_d) on particle adhesion and detachment are studied. The asperity distance is varied in the range 1.2 < L/R_d < 2 and the semi-cylinder radius between 0.5 < R_c/R_d < 0.75. The required particle resolution and domain size are appropriately selected based on numerical studies, and a parametric analysis is performed to investigate the relationship between the contact distance (i.e. half the distance between the particle contact points on two neighbouring semi-cylinders), the asperity distance, the size ratio, and the height of the particle centroid from the plane wall. The drag, lift and torque acting on the spherical particle are measured for different particle Reynolds numbers, asperity distances and sizes or diameters. The detachment of particles from rough surfaces can occur through lift-off, sliding and rolling, and the corresponding detachment models are constructed for the case of rough surfaces. These studies will be the basis for developing Lagrangian detachment models that eventually should allow the optimisation of dry powder inhalator performance through computational fluid dynamics.

使用格子-玻尔兹曼方法对驻留在具有大尺度粗糙度的表面上的微米级球形颗粒进行完全解析的数值模拟。目的是研究表面粗糙度对在 DPI（干粉吸入器）中运输细小药物颗粒的较大载体颗粒与细小药物颗粒分离的影响。通常通过机械处理来修饰载体表面以改变表面粗糙度以降低药物颗粒的粘附力。因此，从载体表面去除药物颗粒相当于从粗糙的平面表面上分离球体。这里考虑了一个直径为 5 μm、雷诺数为 1.0、3.5 和 10 的球体。表面粗糙度被描述为光滑表面上规则间隔的半圆柱形凹凸不平（轴方向垂直于流动方向）。粗糙距离和尺寸比（即半圆柱体的半径与粒子半径的关系）的影响，研究了 R _c / R _d ) 对颗粒粘附和脱离的影响。粗糙距离在 1.2 < L / R _d  < 2范围内变化， 半圆柱半径在 0.5 <  R _c / R _{d 之间} < 0.75。The required particle resolution and domain size are appropriately selected based on numerical studies, and a parametric analysis is performed to investigate the relationship between the contact distance (ie half the distance between the particle contact points on two neighbouring semi-cylinders), the asperity distance 、尺寸比和粒子质心距平面壁的高度。对于不同的颗粒雷诺数、粗糙度距离和尺寸或直径，测量作用在球形颗粒上的阻力、升力和扭矩。颗粒从粗糙表面的脱离可以通过剥离、滑动和滚动发生，并针对粗糙表面的情况构建了相应的脱离模型。