Thanks, Rob. The previous problem of crushing the job in HPC has been identified and resolved.

I have the following queries:

(1) I am injecting particles from a single point. I expect to release the particle in one line (the blue line marked in the below image). Why the particles are distributed throughout the entire domain over time? How can I fix the issue? 

(2) Is there any way to implement when a particle reach (or touch) the gas-liquid interface, the particle will either trap or slip?