It looks like fluid simulation related about solving NS equation, or solving anything else governing fluid-like behaviour. Precisely solving NS equation is work of scientists, if you really need it, it can use a simplified form.
If you only want to implement the flow by simple collision of particles, because current problem is violent rebound, so you can change rebound behaviour of your emitter. It may lies in Solve Forces and Velocity. For example, if the solver handle rebound by adding a rebound force, then you can create a small scalar parameter ReboundScale and multiply it with the rebound force.
However, I haven’t tried it. Wish you can solve it.