# Two-Parameter Probabilistic Model and Experimental Research on Micron Particle Deposition
## Particle Deposition Model
### Two-Parameter Particle Probability Deposition Model
#### 2.3.3 Deposition Calculation Flow of Two-Parameter Particle Probability Deposition  
1. Start the calculation and set the necessary input parameters, including gas-solid two-phase fluid properties, boundary conditions and other setting parameters, the UDF transmission particle deposition desorbed determination criteria, and other conditional functions;
2. According to the input spherical particle force condition function, the Euler-Lagrangian equation is used to calculate the flow field parameters of the gas-solid two-phase particles, and capture the trajectory of the particles in the calculation domain;
3. If particulate matter enters the specified near-wall area (the specified near-wall grid), it is considered that the particulate matter will collide with the target surface (particle deposition wall or particle deposition layer); if the particulate matter is not recognized to enter the specified near-wall area (the specified near-wall grid), it is considered that the particulate matter will collide with the target surface (particle deposition wall or  
Figure 3: Particles–sedimentary particles collision escape process. (**a**) Particulate deposition; (**b**) particle rebound desorption.  
particle deposition layer) in the near-wall grid; then continue to track the trajectory of particulate matter in the calculation domain;
4. For particles that are about to collide, read the collision angle \(\theta_{i}\), particle velocity \(v_{P}\), particle coordinates, center sinking scale \(h\), and other parameters, and calculate the critical stress of the particles \(y\), the equivalent Young's modulus \(E^{*}\), and the sinking area of the specified unit (grid), and intermediate parameters such as particle number \(N\);
5. Call the random function in Fluent to randomly generate an integer \(N_{R}\) greater than or equal to 0 and less than or equal to 100;
6. The collision probability coefficient \(P_{P}\) of particulate matter and deposited particles is obtained through the calculated intermediate parameters, and the size of the \(N_{R}\) and \(P_{P}\) values is compared. If \(N_{R}\times 100\%\geq P_{P}\), the determination criteria for the deposition and desorbing of the particulate matter-particle deposition wall are used for the particulate matter; otherwise, the determination criteria for the deposition and desorbing of the particulate matter-particle deposition layer are used;
7. According to the corresponding criteria, combined with the calculated intermediate parameters, the state coefficient of the particulate matter and particulate matter deposition wall surface \(\Upsilon_{P}\) is obtained. If \(\Upsilon_{P}=0\), it means that the relationship between the particulate matter and particulate matter deposition wall surface at this time is deposition, and the number of particles accumulated in the area of the specified unit (grid) is \(N\) value plus 1, and the particles are removed from the calculation domain; otherwise, it means that the relationship between the particulate matter and the deposited wall of the particulate matter is desorbed; calculate the rebound desorbed velocity \(v_{r}\) of the particulate matter, and the particles re-enter the flow field calculation domain at the same time;
8. Repeat the calculation step (2) until there are no moving particles in the calculation domain, and reach end the calculation.  
The specific calculation process steps are shown in Figure 4: