Phenomenon of Particles Adhering to the Wall in Numerical Simulation

Dear experts,
During recent numerical simulations, I have observed that particles tend to adhere to the wall. Note that the viscous force between particles and the wall is neglected, as illustrated in the figure below.

<img width="698" height="762" alt="Image" src="https://github.com/user-attachments/assets/1667c70a-5ea5-44a4-a4f9-60b54cd2cb4a" />