Table 3.
A summary of the forces acted on various sizes of particle in healthcare facilities
| Authors | Particles size | Forces | Findings |
|---|---|---|---|
| Sadrizadeh et al. (2016b) | 12 µm in mean aerodynamic diameter | Drag force, gravitational force, Saffman’s lift force | Effects of Saffman’s lift force on the fine particles are relatively large, especially in the regions located near the operating room walls |
| Tao et al. (2016) | 2.5 µm in diameter (Density: 700 kg/m3) | Drag force, gravitational force, Saffman’s lift force | The moving manikin causes a pronounced lifting effect on the micron-sized particles, which settle on the floor. The electrostatic and adhesion force at the particle–wall contact surface are disregarded |
| Sadrizadeh et al. (2016a) | 12 µm in mean aerodynamic diameter | Drag force, gravitational force, Brownian force | A modified Discrete Random Walk model by implementing a damping function is required to improve the particle deposition prediction. An isotropic dissipation of the turbulence kinetic energy will cause an over-prediction of particle deposition |
| Wang and Chow (2015) | 0.5 µm, 5 µm, 10 µm, and 20 µm (Density: 600 kg/m3) | Gravitational force, Brownian force, Saffman’s lift force, thermophoretic force | 20 µm particles will settle rapidly onto surfaces while particles fall within the range of 0.5 µm and 20 µm suspended in the air for a longer time |
| Sadrizadeh and Holmberg (2015) | 10 µm in diameter (Density: 1400 kg/m3) | Drag force, gravitational force, Brownian force | Basset, pressure gradient and virtual mass forces are negligible compared to the drag force. Therefore, the variation in particle size had a negligible effect on particle trajectory, and those minor differences are due to the slightly different drag and gravitational forces acting on the particles |
| Sadrizadeh et al. (2014b) | 5 µm, 10 µm and 20 µm in aerodynamic diameter | Drag force, gravitational force | Particle dispersion highly depends on Stokes number (STK). Particles with STK < 0.1 will follow airflow streamlines closely. A small STK value will cause insignificant trajectory differences between 5 µm and 20 µm particles |
| Sadrizadeh et al. (2014a) | 10 µm in diameter (Density: 1400 kg/m3) | Drag force, gravitational force, Saffman’s lift force | The effects of pressure gradient, Basset, virtual mass, thermophoretic and Brownian forces are negligible as compared to drag force |
| Chow and Wang (2012) | 5 µm, 6 µm, 8 µm, 10 µm in diameter (Density: 1000 kg/m3) | Gravitational force, Brownian force | Effects of Brownian force on particle size larger than 0.01 µm are negligible |
| Wang et al. (2012) | 0.3 µm in diameter (Density: 1050 kg/m3) | Drag force, Saffman’s lift force, Brownian force | Gravitational force is insignificant for particles with 0.3 µm in diameter as the particles have approximately the same diffusion properties as a gas |
| Wang and Chow (2011) | 0.5 µm, 5 µm, 10 µm, 20 µm in diameter | Drag force, gravitational force, Brownian force, Saffman’s lift force, thermophoretic force | Brownian and Saffman’s lift forces are significant for the room airflow involving fine particles. The thermophoretic force due to temperature gradient was found to be critical in the case of nonisothermal airflow |
| Liu et al. ( 2009) | 5 µm, 7 µm, 10 µm in diameter (Density: 2000 kg/m3) | Drag force, gravitational force | A small difference was found among particles with a diameter of 5 µm, 7 µm and 10 µm in terms of distribution and trajectory |
| Mousavi and Grosskopf (2015) | 1 µm in diameter | Drag force, gravitational force, Brownian force, Saffman’s lift force, pressure gradient force | A combination of drag, gravitational, Brownian, pressure gradient, Saffman’s lift forces are required to predict the particle trajectory in the hospital’s anteroom and isolation room |
| King et al. (2013) | 2.5 µm in diameter | Drag force, gravitational force, Saffman’s lift force, Brownian force | The differences of particles distributions and flow trajectory are insignificant between 1 µm and 5 µm |