# Two-Parameter Probabilistic Model and Experimental Research on Micron Particle Deposition
## 3 Results and Discussion
### Simulation Results and Test Results
#### 3.3.3 Particle Deposition Morphology of Test Results
After particle deposition, the appearance of the area exposed to the airflow transforms from a flat surface lacking particle deposition to a convex surface with a certain deposition thickness, causing the upstream morphology of the wall surface to change. The airflow velocity at the protrusion where sedimentation has occurred is greater than that at the flat area where sedimentation has not occurred, leading to a higher airflow velocity and lower pressure at the sedimentation site, while the flow velocity and pressure at the non-sedimentation site are relatively smaller and result in a pressure difference. Under this pressure difference, the airflow velocity near the wall follows the airflow path. Particles exhibit a tendency for movement from the undeposited flat area to the already deposited area, making them more prone to adhesive deposition, thereby intensifying the particle adhesion effect in the flow near the wall surface. At the same time, due to the increase in deposition thickness, the capture ability of sliding desorption particles without adhesive deposition on the wall surface is also improved, and such a change increases with the limited increase in the number of adhesive particles; the punctiform deposition presented by sample 2 is intensified into flake deposition, and the deposition appearance is different from the deposition thickness, as shown in Figure 9b, which can be understood as the consistency manifestation of punctiform deposition. Compared with the uniform spot deposition of sample 1, the deposition phenomenon of sample 2 is more obvious, and the boundary between the deposition flake area and the adjacent deposition low-density area is clear, showing the deposition appearance of particles \"conformity\", which is related to the complex turbulence structure near the wall, the morphology specificity of the particles, the orientation of the particles during collision, and the roughness of the wall surface. However, in a mathematical characterization, particles tend to deposit more easily in an area with more deposited particles per unit area. This shows that the mathematical idea of introducing collision probability \(P_{P}\) between the particles and the deposited particles into the particle transport model to adapt a collision criterion is correct. The phenomenon of the selective deposition of particles is not closely related to the influence of constant parameters such as wall roughness on deposition behavior, but more inclined to the description of the irregular turbulent structure near the wall and particle collision probability. The particle transport model characterization is consistent with the experimental simulation results. It should be noted that the particle deposition morphology of sample 1 and sample 2 at the left wall and right wall near the lower wall of the mid-piece are observed, and there are linear deposition low-density areas and partial particle agglomeration adhesion deposition, as shown in Figure 10. The difference is that the boundary of the low-density area of linear deposition of sample 1 is relatively clear, and the spot deposition scale of some particles is relatively small, as shown in Figure 10a; meanwhile, the boundary of the low-density area of linear deposition of sample 2 is relatively blurry, and some particles are aggregated and adhere at similar positions, and the deposition scale is relatively large, and even flake deposition peeled-off and jump collision traces appear, as shown in Figure 10b. deposition, there are four triangular low-velocity regions at the four corners of the gas pipeline. In this region, particles with a smaller inertial force (sample 1) do not easily to enter and escape, so there are line-like low-density regions of deposition and partial particle agglomeration adhesion deposition.